Mainframe Refresher Part-1COBOL-Page: 1 COBOL (COmmon Business Oriented Language) History. Developed by 1959 by a group called COnference on Data Systems Language (CODASYL). First COBOL compiler was released by December 1959. First ANSI approved version – 1968 Modified ANSI approved version – 1974 (OS/VS COBOL) Modified ANSI approved version – 1985 (VS COBOL 2) This book is written based on IBM COBOL for OS/390 V2R2. Speciality. 1. First language developed for commercial application development, which can efficiently handle millions of data. 2. Procedure Oriented Language - Problem is segmented into several tasks. Each task is written as a Paragraph in Procedure Division and executed in a logical sequence as mentioned. 3. English Like language – Easy to learn, code and maintain. Coding Sheet. 1 7 12 COL-A 72 80 COLUMN-B 1-6 7 Page/line numbers – Optional (automatically assigned by compiler) Continuity (-), Comment (*), Starting a new page (/) Debugging lines (D) 8-11 Column A –Division, Section, Paragraph, 01,77 declarations must begin here. 12.72 Column B –All the other declarations/statements begin here. 73-80 Identification field. It will be ignored by the compiler but visible in the source listing. Language Structure. Character Word Clause Statement Sentence Paragraph Section Division Program Digits (0-9), Alphabets (A-Z), Space (b), Special Characters (+ - * / ( ) = $ ; “ > < . ,) One or more characters- User defined or Reserved One or more words. It specifies an attribute for an entry One or more valid words and clauses One or more statements terminated by a period One or more sentences. One or more paragraphs. One or more sections or paragraphs Made up of four divisions Mainframe Refresher Part-1 COBOL-Page: 2 Divisions in COBOL. There are four divisions in a COBOL program and Data division is optional. 1.Identification Division. 2.Environment Division. 3.Data Division. 4.Procedure Division. Identification Division. This is the first division and the program is identified here. Paragraph PROGRAM-ID followed by user-defined name is mandatory. All other paragraphs are optional and used for documentation. The length of user-defined name for IBM COBOL is EIGHT. IDENTIFICATION DIVISION. PROGRAM-ID. PROGRAM NAME. AUTHOR. COMMENT ENTRY. INSTALLATION. COMMENT ENTRY. DATE-WRITTEN. COMMENT ENTRY. DATE-COMPILED. COMMENT ENTRY. SECURITY. COMMENT ENTRY. Security does not pertain to the operating system security, but the information that is passed to the user of the program about the security features of the program. Environment Division. Only machine dependant division of COBOL program. It supplies information about the hardware or computer equipment to be used on the program. When your program moves from one computer to another computer, the only section that may need to be changed is ENVIRONMENT division. Configuration Section. It supplies information concerning the computer on which the program will be compiled (SOURCE-COMPUTER) and executed (OBJECT-COMPUTER). It consists of three paragraphs – SOURCE COMPUTER, OBJECT-COMPUTER and SPECIAL-NAMES. This is OPTIONAL section from COBOL 85. SOURCE-COMPUTER. IBM-4381 (Computer and model # supplied by manufacturer) WITH DEBUGGING MODE clause specifies that the debugging lines in the program (statements coded with ‘D’ in column 7) are compiled. OBJECT-COMPUTER. IBM-4381 (Usually same as source computer) SPECIAL-NAMES. This paragraph is used to relate hardware names to user-specified mnemonic names. 1. Substitute character for currency sign. (CURRENCY SIGN IS litearal-1) 2. Comma can be used as decimal point. (DECIMAL-POINT IS COMMA) 3. Default collating sequence can be changed. It will be explained later. 4. New class can be defined using CLASS keyword. (CLASS DIGIT is “0” thru “9”) Mainframe Refresher Part-1 COBOL-Page: 3 Input-Output Section. It contains information regarding the files to be used in the program and it consists of two paragraphs FILE-CONTROL & I-O CONTROL. FILE CONTROL. Files used in the program are identified in this paragraph. I-O CONTROL. It specifies when check points to be taken and storage areas that are shared by different files. Data Division. Data division is used to define the data that need to be accessed by the program. It has three sections. FILE SECTION describes the record structure of the files. WORKING-STORAGE SECTION is used to for define intermediate variables. LINKAGE SECTION is used to access the external data. Ex: Data passed from other programs or from PARM of JCL. Literals, Constants, Identifier, 1. Literal is a constant and it can be numeric or non-numeric. 2. Numeric literal can hold 18 digits and non-numeric literal can hold 160 characters in it. (COBOL74 supports 120 characters only) 3. Literal stored in a named memory location is called as variable or identifier. 4. Figurative Constant is a COBOL reserved word representing frequently used constants. They are ZERO/ZEROS/ZEROES, QUOTE/QUOTES, SPACE/SPACES, ALL, HIGH-VALUE/HIGH-VALUES, LOW-VALUE/LOW-VALUES. Example: 01 WS-VAR1 PIC X(04) VALUE ‘MUSA’. ‘MUSA ‘ is a non-numeric literal. WS-VAR1 is a identifier or variable. Declaration of variable Level# $ Variable $ Picture clause $ Value clause $ Usage Clause $ Sync clause. FILLER Level# It specifies the hierarchy of data within a record. It can take a value from the set of integers between 01-49 or from one of the special level-numbers 66 77 88 01 level. Specifies the record itself. It may be either a group item or an Elementary item. It must begin in Area A. 02-49 levels. Specify group or elementary items within a record. Group level items must not have picture clause. 66 level. Identify the items that contain the RENAMES clause. 77 level. Identify independent data item. 88 level. Condition names. Variable name and Qualifier Variable name can have 1-30 characters with at least one alphabet in it. Hyphen is the only allowed special character but it cannot be first or last letter of the name. Name should be unique within the record. If two variables with same name are there, then use OF qualifier of high level grouping to refer a variable uniquely. Ex: MOVE balance OF record-1 TO balance OF record-2. Z (ZERO suppression).Z * (But $ Can appear as first place and * as floating. V (Implied decimal point). Half word. 64 bits or 8 bytes is one double word. 0 (Zero). COMP Binary representation of data item. . PIC Clause should not be specified. Most significant bit is ON if the number is negative. S (Sign) + (Plus Sign). S9(10) . 8 Bits is one byte. 32 bits or 4 bytes is one full word.’(comma).CR DB 2. X(Alpha numeric). (F for unsigned positive. Numeric Numeric Edited Non Numeric Exclusive sets 9 (Digit). (Period). . In packed decimal. B (Blank insertion Character). * (ASTERISK). Last nibble is for sign. b (Blank). 4 Bits is one nibble. Ex: Japanese language applications. ‘. each nibble stores one digit. (MVS) Full word. PIC Clause should not be specified. $ + . $***. V ‘. Number of bytes required equals to the size of the data item. COMP-2 Double word floating-point item. (MVS) Double word. PIC clause can contain S and 9 only. C for signed positive and D for signed negative) Formula for Bytes: Integer ((n/2) + 1)) => n is number of 9s. $(Currency Sign) A (alphabet). (MVS) Usage Clause DISPLAY Default. PIC Clause should not be specified. COMP-3 Packed Decimal representation. Two digits are stored in each byte. INDEX It is used for preserve the index value of an array. PICTURE Clause Describes the attributes of variable. 16 bits or 2 bytes is one half word. Refreshing Basics Nibble. 16 bits are used for one character. By default.’ 3. Byte.Mainframe Refresher Part-1 COBOL-Page: 4 FILLER When the program is not intended to use selected fields in a record structure.S9(18) Double word. define them as FILLER. COMP-1 Single word floating point item. G(DBCS) 1. + . every character is stored in one byte. / (Slash) BLANK WHEN ZERO (Insert blank when data value is 0). CR DB (Credit Debit Sign) .**) DBCS (Double Byte Character Set) is used in the applications that support large character sets. FILLER items cannot be initialized or used in any operation of the procedure division. S9(01) – S9(04) Half word. S9(05) – S9(09) Full word.(Minus Sign). REDEFINES The REDEFINES clause allows you to use different data description entries to describe the same computer storage area. SIGN Clause Syntax SIGN IS (LEADING) SEPARATE CHARACTER (TRAILING). -4=M. WS-VAR2 is expected to start at second byte. These items are expected to start at half/full/double word boundaries for faster address resolution. Value of item must not exceed picture size.Mainframe Refresher Part-1 COBOL-Page: 5 VALUE Clause It is used for initializing data items in the working storage section. So this introduces two slack bytes between WS-VAR1 and WS-VAR2. SYNC clause does this but it may introduce slack bytes (unused bytes) before the binary item. Example: 01 WS-DATE PIC 9(06). -125 +125 SYNC Clause and Slack Bytes SYNC clause is specified with COMP. Multiple redefinitions are possible. Size of redefined and redefining need not be the same. -9=R Number -125 +125 TRAILING SIGN (Default) 12N 12E LEADING SIGN J25 A25 LEADING SEPARATE. 01 WS-REDEF-DATE REDEFINES WS-DATE. -8=Q. 10 WS-VAR1 PIC X(02). -1= J. -3=L. -2= K. 01 WS-TEST. . Assumes WS-TEST starts at relative location 0 in the memory. 05 WS-DAY PIC 9(02). It is stored along with last digit. Syntax: VALUE IS literal. WS-VAR1 occupies zero and first byte. 05 WS-YEAR PIC 9(02). -7=P. Redefining declaration should immediately follow the redefined item and should be done at the same level. -6=O. literal-2 Literal can be numeric without quotes OR non-numeric within quotes OR figurative constant. 05 WS-MON PIC 9(02). It cannot be specified for the items whose size is variable. As the comp item in the example needs one word and it is coded with SYNC clause. 10 WS-VAR2 PIC S9(6) COMP SYNC. It is applicable when the picture string contain ‘S’. +1=A +2=B +3=C +4=D +5=E +6=F +7=G +8=H +9=I -0=}. COMP-1 and COMP-2 items. So ‘S’ doesn’t take any space. it will start only at the next word boundary that is 4th byte. VALUES ARE literal-1 THRU | THROUGH literal-2 VALUES ARE literal-1. -5=N. Default is TRAILING WITH NO SEPARATE CHARACTER. 88 or another 66 entry. 05 WS-CHAR4 PIC X(04). 66 ADD-REPSONSE RENAMES WS-CHAR143. JUSTIFIED RIGHT This clause can be specified with alphanumeric and alphabetic items for right justification. 88 MALE VALUE ‘1’ 88 FEMALE VALUE ‘2’ ‘3’. ‘SET FEMALE TO TRUE ‘ moves value 2 to SEX. But all RENAMES entries associated with one logical record must immediately follow that record's last data description entry. the first value will be moved when it is set to true. 05 LK-LENGTH PIC S9(04) COMP. the first two bytes of the field coded in the linkage section will be filled with length and so there are chances of 2 bytes data truncation in the actual field. Linkage section MUST be coded with a half word binary field. LINKAGE section of sub-programs will be explained later. 05 LK-VARIABLE PIC X(08). If length field is not coded. IF SEX=1 can also be coded as IF MALE in Procedure division. . LINKAGE SECTION It is used to access the data that are external to the program. 77. It cannot be used with 66 and 88 level items. It should be declared at 66 level.Mainframe Refresher Part-1 COBOL-Page: 6 RENAMES It is used for regrouping of elementary data items in a record. CONDITION name It is identified with special level ‘88’. A condition name specifies the value that a field can contain and used as abbreviation in condition checking. It need not immediately follows the data item. OCCURS Clause OCCURS Clause is used to allocate physically contiguous memory locations to store the table values and access them with subscript or index. JCL can send maximum 100 characters to a program thru PARM. 01 WS-REPSONSE. 05 WS-CHAR143 PIC X(03). Detail explanation is given in Table Handling section. 01 SEX PIC X. which is being renamed. If multiple values are coded on VALUE clause. prior to actual field. RENAMES cannot be done for a 01. 01 LK-DATA. If the receiving field width is smaller than sending field then excess digits. Syntax: MOVE identifier1/literal1/figurative-constant TO identifier2 (identifier3) Multiple move statements can be separated using comma. Unfilled positions are filled with zero. Ex: END-ADD END-IF END-EVALUATE The period at the end of any sentence. semicolons. Zero suppression or insertion of editing symbols takes places according to the rules of editing pictures. Ex: MOVE ADD EXIT GO TO Decide the truth or false of relational condition and based on it. When the length of receiving field is shorter than that of sending field. When an alphanumeric field is moved to a numeric or numeric-edited field. alphanumeric or alphanumeric-edited data field receives the data from left to right. Section name should be unique within the program and paragraph name should be unique within the section. blanks or the keyword THEN. This is the last division and business logic is coded here. Procedure division statements are broadly classified into following categories. It has user-defined sections and paragraphs. Alphanumeric Move Rules: Alphabetic. Any unfilled field of the receiving filed is filled with spaces. the item is moved as if it were in an unsigned numeric integer mode. EVALUATE Directs the compiler to take specific action during compilation. to the left and/or to the right of the decimal point are truncated. The unaccomodated characters on the right of the sending field are truncated. Ex: IF.Mainframe Refresher Part-1 COBOL-Page: 7 Procedure Division. Ex: COPY SKIP EJECT Terminate the scope of conditional and imperative statements. MOVE Statement It is used to transfer data between internal storage areas defined in either file section or working storage section. Statement Type Imperative Conditional Compiler Directive Explicit Scope terminator Implicit Scope terminator Meaning Direct the program to take a specific action. execute different paths. MOVE CORRESPONDING group-1 TO group-2 . then receiving field accepts characters from left to right until it is filled. terminates the scope of all previous statements not yet terminated. Numeric move rules: A numeric or numeric-edited item receives data in such a way that the decimal point is aligned first and then filling of the receiving field takes place. CORRESPONDING can be used to transfer data between items of the same names belonging to different group-items by specifying the names of group-items to which they belong. Samples for understanding MOVE statement (MOVE A TO B) Picture of A Value of A Picture of B PIC 99V99 PIC 99V99 PIC 99V999 PIC9(05)V9(03) PIC 9(04)V9(02) PIC 99V99 PIC X(04) 12.35 0012.34 321.34 MUS ARITHMETIC VERBS All the possible arithmetic operations in COBOL using ADD.99 XBXBXB Value of B after Move 012.The resultant value of operation exceeds any of the operand size.9 PIC $$$.35 12.2 $.Mainframe Refresher Part-1 COBOL-Page: 8 Group Move rule When MOVE statement is used to move information at group level.3500 2. 2.543 23. This is regardless of the description of the elementary items constituting the group item. the movement of data takes place as if both sending and receiving fields are specified as alphanumeric items. MULTIPLY and DIVIDE are given below: Arithmetic Operation ADD A TO B ADD A B C TO D ADD A B C GIVING D ADD A TO B C SUBTRACT A FROM B SUBTRACT A B FROM C SUBTRACT A B FROM C GIVING D MULTIPLY A BY B MULTIPLY A BY B GIVING C DIVIDE A INTO B DIVIDE A INTO B GIVING C DIVIDE A BY B GIVING C DIVIDE A INTO B GIVING C REMAINDER D A A A A A A A B A+B B B A+B B-A B C D C C A+C A+B+C+D A+B+C A B C A A A*B B A*B A A B/A B B/A A B A/B A B Integer (B/A) C-(A+B) C-(A+B) Integer remainder GIVING is used in the following cases: 1. .35 12.To retain the values of operands participating in the operation.543 23.345 54321.34 MUSA PIC 999V99 PIC 9999V9999 PIC 9V99 PIC 9(03)V9(03) PIC ZZZ99. SUBTRACT.24 00. ON SIZE ERROR clause is coded to trap such size errors in arithmetic operation. Syntax: INITIALIZE identifier-1 REPLACING (ALPHABETIC/ALPHANUMERIC/ALPHA-NUMERIC-EDITED NUMERIC/NUMERIC-EDITED) DATA BY (identifier-2 /Literal-2) .. + For ADD. It is suggested to use them. This can be overridden by REPLACING option of INITIALIZE. alphanumeric and alphanumeric-edited items to SPACES and numeric and numeric-edited items to ZERO. COMPUTE Complex arithmetic operations can be carried out using COMPUTE statement. some compiler will do rounding for every arithmetic operation and so the final result would not be precise.99)) =120 or ROUNDED(142. If this is coded with arithmetic statement. END-SUBTRACT. FILLER. any operation that ended with SIZE error will not be carried out but the statement follows ON SIZE ERROR will be executed. It is usually coded after the field to be rounded.ROUNDED REMAINDER Caution: Don’t use for intermediate computation. ON SIZE ERROR If A=20 (PIC 9(02)) and B=90 (PIC 9(02)). END-COMPUTE). CORRESPONDING is available for ADD and SUBTRACT only.Exponentiation 3. ADD A TO B ON SIZE ERROR DISPLAY ‘ERROR!’.Addition and Subtraction Caution: When ROUNDED is coded with COMPUTE.Be cautious when using ROUNDED keyword with COMPUTE statement. We can use arithmetic symbols than keywords and so it is simple and easy to code. / for DIVIDE and ** for exponentiation. ADD A B GIVING C ROUNDED.3205) = 142 So the result can be 120 or 142. (END-ADD. the computer will always round the result to the PICTURE clause specification of the receiving field. INITIALIZE sets the alphabetic. END-DIVIDE. * for MULTIPLY.Parentheses 2. All arithmetic operators have their own explicit scope terminators. END-MULTIPLY.99 Result: (ROUNDED(ROUNDED(12. INITIALIZE VALUE clause is used to initialize the data items in the working storage section whereas INITIALIZE is used to initialize the data items in the procedure division.Multiplication and Division 4. . OCCURS DEPENDING ON items are not affected.Mainframe Refresher Part-1 COBOL-Page: 9 ROUNDED option With ROUNDED option. ADD A TO B will result 10 in B where the expected value in B is 110. DIVIDE. Rule: Left to right – 1.95) *10.for SUBTRACT. 77 A PIC 999 VALUE 10 COMPUTE A ROUNDED = (A+2. It is prefixed with REMAINDER keyword ONLY in DIVIDE operation.95) * ROUNDED(10. PROGRAM COLLATING SEQUENCE IS alphabet-name 2. EBCDIC (Ascending Order) Special Characters a-z A-Z 0-9 ASCII (Ascending Order) Special Characters 0-9 A-Z a-z Default collating sequence can be overridden by an entry in OBJECT-COMPUTER and SPECIAL NAMES paragraphs. TIME. . GOBACK can be coded in main program as well as sub-program as the last statement. At the time of execution. It returns control back to OS. The result of arithmetic and alphabetic comparison would be same in both collating sequences whereas the same is not true for alphanumeric comparison. Code the PROGRAM COLLATING SEQUENCE Clause in the Object computer paragraph. IBM and IBM Compatible machine use EBCDIC collating sequence whereas most micro and many mainframe systems use ASCII collating sequence.Mainframe Refresher Part-1 COBOL-Page: 10 ACCEPT ACCEPT can transfer data from input device or system information contain in the reserved data items like DATE. Map the alphabet-name in the SPECIAL-NAMES paragraph as follows: ALPHABET alphabet-name is STANDARD-1 | NATIVE NATIVE stands for computer’s own collating sequence whereas STANDARD-1 stands for ASCII collating sequence. 1. By default display messages are routed to SYSOUT. EXIT PROGRAM is the last executable statement of sub-program. It just gives the control back from where it received the control. DATE option returns six digit current date in YYYYMMDD DAY returns 5 digit current date in YYDDD TIME returns 8 digit RUN TIME in HHMMSSTT DAY-OF-WEEK returns single digit whose value can be 1-7 (Monday-Sunday respectively) DISPLAY It is used to display data. EXIT PROGRAM & GO BACK STOP RUN is the last executable statement of the main program. ACCEPT WS-VAR1 (FROM DATE/TIME/DAY/OTHER SYSTEM VARS). If FROM Clause is not coded. Syntax: DISPLAY identifier1| literal1 (UPON mnemonic name) STOP RUN. batch program will ABEND if there is no in-stream data from JCL and there is no FROM clause in the ACCEPT clause. Collating Sequence There are two famous Collating Sequence available in computers. then the data is read from terminal. DAY. It returns control back to main program. The permitted relation conditions are =. sign test can be negated using NOT. Here TOTAL=8 is implied operation. It can be done as follows IF identifier is NUMERIC/ALPHABETIC/ALPHABETIC-HIGHER/ ALPHABETIC-LOWER You can define your own classes in the special names paragraph. If you forgot the difference between statement and sentence. The control is just passed to next STATEMENT. Any simple. NEXT SENTENCE passes the control to the next SENTENCE. 2 and 4 are TRUE and condition 3 is FALSE.Mainframe Refresher Part-1 COBOL-Page: 11 IF/THEN/ELSE/END-IF The most famous decision making statement in all language is ‘IF’. But it is not always true that NOT NEGATIVE is equal to POSITIVE. It can be used in the following way. implicit scope terminator. >. <. The syntax of IF statement is given below: IF can be coded without any ELSE statement. <> CONTINUE is no operation statement. SIGN test and CLASS test SIGN test is used to check the sign of a data item. IF identifier is DIGIT Negated conditions. This rule can be overridden by using parentheses. It is advised to use END-IF. class. relational. <=. refer the first page. THEN is a noise word and it is optional. explicit scope terminator for the IF statements than period. it is not always necessary to specify both operands for each condition. Implied operand: In compound conditions. IF condition1 AND condition2 THEN Statement-Block-1 ELSE IF condition3 THEN CONTINUE ELSE IF condition4 THEN Statement-Block-2 ELSE NEXT SENTENCE END-IF END-IF END-IF Statement-Block-2 will be executed only when condition 1. We have defined a class DIGIT in our special names paragraph. IF TOTAL=7 or 8 is acceptable. ANDs are evaluated first from left to right. It can be done as follows – IF identifier is POSITIVE/NEGATIVE/ZERO CLASS test is used to check the content of data item against pre-defined range of values. (Example ZERO) . >=. If ORs & ANDs are used in the same sentence. followed by ORs. Break statement is not needed.. as it is so in other languages. Multiple IF statements can be efficiently and effectively replaced with EVALUATE statement. 3.Mainframe Refresher Part-1 COBOL-Page: 12 EVALUATE With COBOL85.) WHEN OTHER imperative statement END--EVALUATE 1. 2. expression or the keyword TRUE/ FLASE and respectively objects can be values. Sample EVALUATE SQLCODE ALSO TRUE WHEN 100 ALSO A=B imperative statement WHEN -305 ALSO (A/C=4) imperative statement WHEN OTHER imperative statement END-EVALUATE . the control is automatically come to the next statement after the END-EVALUATE. After the execution of one of the when clauses.If none of the WHEN condition is satisfied.. General Syntax EVALUATE subject-1 (ALSO subject2.) WHEN object-3 (ALSO object4. TRUE/FALSE or any condition.Subject can be variable. then WHEN OTHER path will be executed. we use the EVALUATE verb to implement the case structure of other languages.Number of Subjects in EVALUATE clause should be equal to number of objects in every WHEN clause.) WHEN object-1 (ALSO object2. Any complex condition can be given in the WHEN clause.. If the condition is again false. When sets of statements are used only in one place then we can group all of them within PERFORM END-PERFORM structure. .WHILE) With TEST AFTER. otherwise the paragraphs will be performed indefinitely.Mainframe Refresher Part-1 COBOL-Page: 13 PERFORM STATEMENTS PERFORM will be useful when you want to execute a set of statements in multiple places of the program. This is equal to DO. PERFORM PARA-1 THRU PARA-N N TIMES.INLINE PERFORM. (Functions like DO. PERFORM PARA-1 THRU PARA-N UNTIL condition(s).PERFORM PARA-1 WITH TEST BEFORE/AFTER UNTIL condition(s). Statement1 Statement2. Once the paragraph is executed. Write all the statements in one paragraph and invoke it using PERFORM wherever needed. PARA-1 is executed once and then the condition is checked. PERFORM PARA-1 THRU PARA-N. 1. PERFORM PARA-1.END structure of other languages. DISPLAY ‘PARA-1 executed’ STOP RUN. then named paragraph(s) will not be executed at all. PERFORM ADD A TO B MULTIPLE B BY C DISPLAY ‘VALUE OF A+B*C ‘ C END-PERFORM 3. 7.SIMPLE PERFORM. 4. 2. 6. N can be literal defined as numeric item in working storage or hard coded constant. the control comes back to next statement following the PERFORM. PERFORM PARA-1 THRU PARA-N VARYING identifier1 FROM identifier 2 BY identifier3 UNTIL condition(s) Initialize identifier1 with identifier2 and test the condition(s). The identifiers used in the UNTIL condition(s) must be altered within the paragraph(s) being performed. (Functions like DO-UNTIL) Refer Table session for eighth type of PERFORM. If the condition is false execute the statements in PARA-1 thru PARA-N and increment identifier1 BY identifier3 and check the condition(s) again.. then PARA1 is executed and this is the default. It executes all the instructions coded in PARA-1 and then transfers the control to the next instruction in sequence. PARA-1. repeat this process till the condition is satisfied. With TEST BEFORE. 5. Condition is checked first and if it found false. This is called INLINE PERFORM. If the condition in the UNTIL clause is met at first time of execution. All the paragraphs between PARA-1 and PARA-N are executed once. are permitted as long as they are within the range of named paragraphs. When using the THRU option of PERFORM statement. COBOL reserved word that performs NOTHING. The readability of the program will also be badly affected. GO TO Usage: In a structured top-down programming GO TO is not preferable. 100-STEP-1.Mainframe Refresher Part-1 COBOL-Page: 14 EXIT statement. DISPLAY ‘VALUE OF C:’ C. PERFORM 100-STEP1 THRU STEP-4 . ADD A TO B GIVING C. It offers permanent control transfer to another paragraph and the chances of logic errors is much greater with GO TO than PERFORM. i. MULTIPLY C BY D. IF D = ZERO DISPLAY ‘MULTIPLICATION NOT DONE’ GO TO 300-STEP3 END-IF.. It is used as a single statement in a paragraph that indicate the end of paragraph(s) execution. 300-STEP-3. branches or GO TO statements. 200-STEP-2. This kind of Controlled GO TO is fine with structured programming also! . But still GO TO can be used within the paragraphs being performed.e. Here GO TO used within the range of PERFORM. EXIT must be the only statement in a paragraph in COBOL74 whereas it can be used with other statements in COBOL85. -Sequential search. in turn translated to displacement to access elements and so slower than INDEX access. 01 WEEK-ARRAY VALUE ‘MONTUEWEDTHUFRISATSUN’. ADD WS-SAL(SUB) WS-SAL(SUB + 1) TO WS-SAL(SUB + 2). Sometimes. 88 levels. You have to do by yourself and the best way is. SEARCH and PERFORM statements. It can be defined as elementary or group item. Simple tables can be initialized in the following way. 05 WS-DAYS OCCURS 31 TIMES DEPENDING ON WS-OCCURENCE. Relative subscripts and relative indexes are supported only in COBOL85.Mainframe Refresher Part-1 COBOL-Page: 15 TABLES An OCCURS clause is used to indicate the repeated occurrences of items of the same format in a structure. The table look-up can be done in two ways. . Array Items can be accessed using INDEX or subscript and the difference between them are listed in the table. Sl # 1 2 3 4 5 Subscript Working Storage item It means occurrence Occurrence. OCCURS clause is not valid for 01. Subscripts can be modified by any arithmetic statement. Initialization of large table occurrences with specific values are usually done using perform loops in procedure division. Obviously. INDEX can only be modified with SET. Dynamic array is the array whose size is decided during runtime just before the access of first element of the array. It can be used in any arithmetic operations or for display. Literals used in relative subscripting/indexing must be an unsigned integer. you may face a question like how to randomly access the information in the sequential file of 50 records that contains all the designation and the respective lower and higher salary information. 77. IF MONTH = ‘FEB’ MOVE ‘28’ to WS-OCCURRENCE. load the file into a working storage table in the first section of the program and then access as you wish. 05 WS-WEEK-DAYS OCCURS 7 TIMES PIC X(03). -Binary search. Index Internal Item – No need to declare it. It cannot be used for arithmetic operation or for display purpose. It means displacement Faster and efficient. OS does not allow you to randomly access the sequence file. 01 WS-MONTH-DAY-CAL. SET indexname-1 TO 1. Binary SEARCH When the size of the table is large and it is arranged in some sequence – either ascending or descending on search field. Index need not be set to 1 before SEARCH ALL. 4 Multiple WHEN conditions can be coded. 5. else repeat the process with the left or right half depending on where the item lies. Condition-1. SET statement Syntax: SET index-name-1 TO/UP BY/DOWN BY integer-1.Mainframe Refresher Part-1 COBOL-Page: 16 Sequential SEARCH During SERIAL SEARCH. then index or subscript is incremented by one and the next entry is searched and the process continues until a match is found or the table has been completely searched. Only = is possible. . SEARCH identifier-1 AT END display ‘match not found:’ WHEN condition-1 imperative statement-1 /NEXT SENTENCE WHEN condition-2 imperative statement-2 /NEXT SENTENCE END-SEARCH Identifier-1 should be OCCURS item and not 01 item. Because if it is not coded and element looking for is not found. Though AT END Clause is optional. then BINARY SEARCH would be the efficient method. SEARCH ALL identifier-1 AT END imperative-statement-1 WHEN dataname-1 = identifier-2/literal-1/arithmetic expression-1 AND dataname-2 = identifier-3/literal-2/arithmetic expression-2 END-SEARCH. the table look-up is completed. If the condition is not met. Compare the item to be searched with the item at the center. Condition-2 compares an input field or search argument with a table argument. 6 7 Index should be set to 1 before using SEARCH Prefer when the table size is small Binary SEARCH SEARCH ALL Table should have INDEX Table should be in sorted order of the searching argument. Only AND is possible in compound conditions. Prefer when the table size is significantly large. If it matches fine. Only one WHEN condition can be coded. it is highly recommended to code that. Sl # 1 2 3 Sequential SEARCH SEARCH Table should have INDEX Table need not be in SORTED order. the first entry of the table is searched. There should be ASCENDING/DESCENDING Clause. then the control simply comes to the next statement after SEARCH where an invalid table item can be referred and that may lead to incorrect results / abnormal ends. If the condition is met. Any logical comparison is possible. Identifier-2 and identifier-3 are subscripted items and dataname-1 and dataname-2 are working storage items that are not subscripted. . 15 EMP-NUMBER PIC 9(04).level OCCURS.COND=(4. DBCS. Installation defaults. FLAGMIG. ZWB DUMP. Installation defaults. DLL. the procedure portion of the listing will contain line numbers.PROCESS or CBL statement with compiler options. OBJECT. Any CALL identifier statements that cannot be resolved in your program are also treated as dynamic calls. QUOTE. RESIDENT is also put into effect. then you can compile your program with NOADV. SSRANGE. FLAGSTD. EXPORTALL. The compiler adds one byte prefix to the original LRECL of printer files for printing control purpose. NUMPROC. LIST is used to produce listing a listing of the assembler language expansion of your code. statement references. CMPR2. XREF COMPILE. LIST will be ignored.Compiler options can be passed to COBOL Compiler Program (IGYCRCTL) through the PARM in JCL. Options coded on JCL PARM parameters 4. OFFSET is used to produce a condensed Procedure Division listing. If you are manually populating printing control character in the program. Precedence of Compiler Options 1. ANALYZE. 3. 2. and the location of the first instruction generated for each . DYNAM: Use DYNAM to cause separately compiled programs invoked through the CALL literal statement to be loaded dynamically at run time. If you use both. WORD DATEPROC. VBREF. fixed by the installation. MAP. DECK.ADVANCING keyword. NAME. (Lowest Precedence). AWO. With OFFSET. SPACE. OUTDD. INTDATE.Mainframe Refresher Part-1 COBOL-Page: 33 Ways of overriding the default options 1. TERMINAL. but not fixed. (Highest precedence). FASTSRT. YEARWINDOW LANGUAGE. PGMNAME ADV. DYNAM causes dynamic loads (for CALL) and deletes (for CANCEL) of separately compiled programs at object time. EXIT. FLAG. Options coded on PROCESS /CBL statement 3. CURRENCY. SEQUENCE. OFFSET. 2. LIB. NUMBER. LIST/OFFSET: LIST and OFFSET are mutually exclusive. OPTIMIZE. can be placed before the identification division. When you specify DYNAM. IDLGEN ADV: It is meaningful if your program has any printer files with WRITE. SOURCE.. LIST. TYPECHK ADATA.If the organization uses any third party product or its own utility then these options can be coded in the pre-defined line of the utility panel. LINECOUNT. TRUNC. The complete list of compiler option is in the table: Aspect Source Language Date Processing Maps and Listing Object Deck generation Object Code Control Debugging Other Compiler Option APOST. usually S0C4. If the program is compiled with NOSSRANGE. Refer JCL session for more details. where all the to ws-buffer. 01 Filler. Procedure Division. s9(8) Comp. *----------------------------------------------------------------* * Call the TSO/E Service Routine to execute the TSO/E command * *----------------------------------------------------------------* CALL 'IKJEFTSR' Using ws-flags. X(4) Value X'00010001'.ws-return-code. SMSTSOEV. s9(8) Comp. 05 ws-dummy Pic 05 ws-return-code Pic 05 ws-reason-code Pic 05 ws-info-code Pic 05 ws-cppl-address Pic 05 ws-flags Pic 05 ws-buffer Pic 05 ws-length Pic s9(8) Comp. Interview Questions(IQ): * Says importance and possibility of the question in an interview. 1.ws-cppl-address. *----------------------------------------------------------------* * Check that the ALLOCATE command worked * *----------------------------------------------------------------* DISPLAY 'ALLOCATE Worked ! ' Upon Syspunch. Return-code=' ws-return-code ' Reason-code=' ws-reason-code MOVE ws-return-code to Return-code STOP RUN. s9(8) Comp Value 256. IF ws-return-code > zero DISPLAY 'IKJTSOEV Failed.Mainframe Refresher Part-1 COBOL-Page: 35 * TSO/E Programming Services manual.Difference between Next Sentence and Continue *** . IF ws-return-code > zero DISPLAY 'IKJEFTSR Failed. Return-code=' ws-return-code ' Reason-code=' ws-reason-code 'Info-code=' ws-info-code MOVE ws-return-code to Return-code STOP RUN. Program-ID. * ****************************************************************** Identification Division. *----------------------------------------------------------------* * Call IKJTSOEV to create the TSO/E environment * *----------------------------------------------------------------* CALL 'IKJTSOEV' Using ws-dummy.ws-reason-code. s9(8) Comp.ws-dummy. X(256).ws-reason-code. Data Division. Working-Storage Section.ws-buffer.ws-length ws-return-code. STOP RUN. s9(8) Comp. ***** 3.What are SAME AREA and SAME RECORD AREA? * 31.Can occurs be coded in 01 level? ***** 15. Yes/No ** 22.Are multiple 01 levels supported in file section? ** 16.How do you set return code from the program? *** 12.Subscript and Index difference and when you prefer what? **** 8.What is UT-S means with respect to SELECT statement? * 20.Case structure.What is in line PERFORM and when will you use it? **** 27.Difference between section and paragraph ***** 14.Difference between COBOL74 (OS/VS COBOL) and COBOL85 (VS COBOL2) **** 7.What is SYNC Clause? ** 26.To use SEARCH ALL.How to swap two variables without third variable? * 34. Do while. the table should be in sorted order. Should know how to read COMP-3 data. Comp-1. Is dynamic allocation possible in COBOL? If yes. BLL equivalent in COBOL *** 13.How to create a report in COBOL program? *** 24.What is INSPECT statement? *** 28. Sub-string. **** 9.What is limit of linkage section? * Answers for selected questions: . How will I load the table in SORTED order? You should not sort in JCL.Reference modification.Sort algorithms ** 18. How? * 32.Which VSAM type is fastest? Relative key is part of file section? ** 23.What is the purpose of USE statement? * 30.Identifying and making Static and Dynamic call ***** 4.What are the various ways of passing data from JCL to Program and how to receive them in Program? ***** 6.How to submit a JCL from COBOL program? **** 25.Compiler and Link edit option – SSRANGE MAP LIST OFFSET RENT RESIDENT DYNAM and AMODE/RMODE *** 10.Mainframe Refresher Part-1 COBOL-Page: 36 2.How to get the actual length of alphanumeric item? ** 19.Comp.Binary and Sequential search and when you prefer what? ***** 5. Comp-2 and Comp-3 difference and how many bytes occupied by each.Can I rewrite a sequential file in TAPE? * 21.How to make a call by content in COBOL? *** 11. The PDS member data is not in sorted order. I am loading the table from one of the PDS members. What is the difference between ON SIZE ERROR and ON OVERFLOW? * 33. Do Until.COMP-3 items are always better than COMP in terms of memory.Various ways of overriding default compiler options ** 17. ** 29. you should call your installation specific assembler routine or ILBOABN0 with the ABEND code you want... (IQ 20) LENGTH function counts space also as a character. INSPECT is also not useful as the string may contain 1. What are the sort algorithms? (IQ 17 and 28) . It is a half word binary. Ex: MOVE 1000 to RETURN-CODE. PERFORM VARYING WS-SUB-NAME FROM LENGTH OF WS-VAR BY -1 UNTIL END-FOUND OR WS-SUB-NAME = 0 IF WS-NAME-CHK(WS-SUB-NAME:1) NOT EQUAL TO SPACE MOVE 'Y' TO WS-END-OF-FIELD DISPLAY 'LENGTH ' WS-SUB-NAME END-IF END-PERFORM How to pass user return code and user ABEND from the COBOL program to the JCL? RETURN-CODE is a special register and its content is moved to register15 when the control is given back to OS. WS-ABEND-CODE is the variable that has ABEND-CODE. So the logic would be ” Read from right until you read first noon-space character”. What should be the LRECL of printer files? Use 133 character records in your program and set the print control character yourself.Mainframe Refresher Part-1 COBOL-Page: 37 What is the limit of working storage and linkage section limit? (IQ 34) Working storage and Linkage section limit of COBOL85 is 128MB (COBOL741MB) 77.. For ABEND. So we cannot use that function for our purpose.01-49 level item limit in COBOL85 is 16MB (COBOL74-1MB) How to swap the values of two variables without an intermediate variable?(IQ 33) Let the variables be A and B Way 1:COMPUTE A = A+B Way 2: COMPUTE A=A*B COMPUTE B = A-B COMPUTE B=A/B COMPUTE A = A-B COMPUTE A=A/B I have retrieved a value from DB2 VARCHAR column.n spaces in between and that needs to be counted.... So move the return code to this register in the program.. You need the compiler option ADV for this and the JCL would have RECFM=FBA... LRECL=133 Use 132 character records in the program and have WRITE . This sets return code as 1000 for the step that executes this program. (Ex: WS-VAR = ‘muthu$sara$‘ $ is 1-n spaces...ADVANCING put in the print control.LRECL=133.) How to get the length of the WS-VAR in COBOL program? I should not count right hand spaces. CALL ‘ILBOABN0’ USING WS-AB-CODE. In this case your JCL would have RECFM=FB. PIC S9(04) COMP occupies 2 bytes whereas PIC S9(04) COMP-3 occupies 3 bytes. COMP-3 items are always better than COMP with respect to memory usage (IQ 21)? No.Maximum 1 comparison 1. Shuttle Sort: In the first pass only first two elements are compared and sorted and in the second pass. 50 & 8 -> 50 is great. In the first pass. and I with I-1 and so on until top of the table is reached or no-exchange in a comparison. How will you do that? . In between. First two-bytes contain class number and next two-bytes contain student number. 20 & 9 -> 20 is great so swap (1 9 20 50). so swap. I want to read all the students in class ‘02’. Array: 1 20 9 50 8 First Pass: (Maximum 4 comparisons for 5 elements) 1. PIC S9(18) COMP occupies 8 bytes whereas PIC S9(18) COMP-3 occupies 10 bytes. 8 & 1 -> no change and stop. 20 & 8 -> 20 is great so swap (1 9 8 20 50) Third Pass: (1 9 8 20 50) – (Maximum 2 comparisons for 5 elements) 1 & 9 -> no change. 9 & 8-> change (1 8 9 20 50) Fourth Pass: (1 8 9 20 50) – (Maximum 1 comparison for 5 elements) 1 & 9 -> no change Note: You can come out of sort when you find ‘no change’ in all the comparisons of a pass. PIC S9(09) COMP occupies 4 bytes whereas PIC S9(09) COMP-3 occupies 5 bytes. proceeds to sort the first (I+1) elements by comparing I+1 th element with I. 8 & 20-> Change ( 1 9 8 20 50) 8 & 9 -> Change (1 8 9 20 50) . third element is compared with two and one and it is placed in the right position. they are swapped. the key with largest value will be moved to the last position and n-1 passes needed to sort the whole table. 20 & 50 -> no change. if any pass results no interchange it implies that the table is in sorted order. 20->no change Second Pass: Three elements (1 20 9) – Maximum 2 comparisons 9 & 20 -> change (1 9 20) 9 & 1 -> no change Third Pass: Four elements (1 9 20 50) – Maximum 3 comparisons 50 & 20 -> no change and stop (no need for any other comparison) Fourth Pass: Five elements (1 9 20 50 8) – Maximum 4 comparisons 8 & 50 -> change ( 1 9 20 8 50) . I have a KSDS Students file with 4 bytes key. (1 9 20 8 50) Second Pass: (1 9 20 8 50) . 20->no change. In the ith pass. it assumes that I elements are in already sorted order.Mainframe Refresher Part-1 COBOL-Page: 38 Bubble Sort: Consecutive elements are compared and keys of two elements are not in proper order.(Maximum 3 comparison for 5 elements) 1 & 9-> no change. 9 & 20 -> no change. COMP items occupy less space than COMP-3 items at boundaries. Note: You can come out of pass if you find one ‘no change’ Shuttle sort is better than bubble sort for sorting arrays with more than 10 elements. Array: 1 20 9 50 8 First Pass: Two elements (1 20) . Issue the START command with KEY IS GREATER THAN clause. You can do these moves by reference modification operator or de-grouping the four-byte field into two two-byte fields in the file section. Start reading the file in loop until first two-bytes is not equal to 2.Mainframe Refresher Part-1 COBOL-Page: 39 Allocate the file with dynamic access mode. Move ‘02’ to first two-bytes of the key and low-values to next two-bytes of the key. .