1. Programming in COBOL-85 For IBM Mainframe System 390
Jyothi Sridhar Kini
E&R, Infosys
Mail-id:
Phone:
1/14/2019 9:43 AM
E&R Dept., ITLInfosys

2. Objectives of the Session
(1) Index sequential file organization. (2) Relative file organization.
(3) The COPY verb. (4) The CALL verb.
(5) Demonstration of sample programs.
1/14/2019 9:43 AM
E&R Dept., ITLInfosys

3. Indexed file organization
Essentially comprises of two files namely (1) A data file and (2) An index file.
Provides both sequential and random access.
Slowest of all types of file organizations.
Facilitates the use of multiple alphanumeric keys.
Moderately storage efficient.
1/14/2019 9:43 AM
E&R Dept., ITLInfosys

4. Example Data File Index File BU103 Roopa 19 BU101 Deeptha 20
REGNO NAME AGE
BU Roopa
BU Deeptha
BU Bhavana
Index File
REGNO ADDRESS
BU a3c2
BU a3d4
BU b943
Index
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E&R Dept., ITLInfosys

5. Indexed and Relative Files
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E&R Dept., ITLInfosys

6. ED Entries for Indexed Files[ ]
ENVIRONMEN T
RANDOM
DYNAMIC
DIVISION .
INPUT -
OUTPUT
SECTION
FILE
CONTROL
SELECT
LogicalFN
] FileName
ASSIGN
TO FileS
pec
ORGANIZATI ON IS
INDEXED
ACCESS
MODE IS
SEQUENTIAL
RECORD
KEY IS U
niqueRecKe y
ALTERNATE
RECORD KE
Y IS AltKe
WITH
DUPLICATES
STATUS
IS File
Status ì í î ü ý þ ï é ë ê ù û ú
1/14/2019 9:43 AM
E&R Dept., ITLInfosys

7. About index sequential file
An indexed file in Cobol can be accessed either sequentially or randomly.
When accessed randomly, the sequence in which the records are accessed can be specified by the data item called record key
1/14/2019 9:43 AM
E&R Dept., ITLInfosys

8. Prime key and alternate key
The field which is specified in the RECORD KEY clause is known as prime key
Alternate key for the file can be specified using the ALTERNATE KEY clause
Alternate keys are unique by default
If the file has duplicate values for the alternate key then WITH DUPLICATES phrase should be specified
1/14/2019 9:43 AM
E&R Dept., ITLInfosys

9. Indexed File Verbs OPEN
INPUT
OUTPUT
I-O
FileName ì í ï î ü ý þ
1/14/2019 9:43 AM
E&R Dept., ITLInfosys

10. READ To read the records in the file in direct fashion
To read the records in the file in sequential fashion
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E&R Dept., ITLInfosys

11. Write and Rewrite
The records are written to the logical position as determined from the value of the record key
REWRITE statement requires that the file must be opened in the I-O mode
1/14/2019 9:43 AM
E&R Dept., ITLInfosys

12. DELETE
The record last read by the READ statement is deleted in case of sequential read
In case of random read the record to be deleted is specified in the record key option
File must be opened in the I-O mode
1/14/2019 9:43 AM
E&R Dept., ITLInfosys

13. START statement
The START positions the file to the first logical record whose record key satisfies the condition specified by the key phrase
The access mode must be SEQUENTIAL OR DYNAMIC
File must be opened in the I-O or input mode.
1/14/2019 9:43 AM
E&R Dept., ITLInfosys

14. START
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E&R Dept., ITLInfosys

15. Relative Files
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E&R Dept., ITLInfosys

16. Select and Assign for Relative Files

17. Relative File Verbs
All the verbs discussed with INDEXED files holds good in Relative Organization too.
Point to remember is that relative key is not part of Relative record and is declared as WS variable and must contain proper values.

18. File ORGANIZATIONs - A comparative study
SEQUENTIAL INDEXED RELATIVE
Slow when the hit Slowest Direct Access Wasteful of storage
hit rate is low organization if the file is only
partially populated.
Complicated to Especially slow while Complicated to
change. (Insert, adding or deleting of program.
Delete) records.
1/14/2019 9:43 AM
E&R Dept., ITLInfosys

19. File ORGANIZATIONs - A comparative study
SEQUENTIAL INDEXED RELATIVE
Simplest Can use multiple, Only a single,
ORGANIZATION Alphanumeric keys numeric key
is allowed.
Most storage Not very storage Least storage
efficient efficient Efficient.
1/14/2019 9:43 AM
E&R Dept., ITLInfosys

20. Demonstration of Sample Programs 1/14/2019 9:43 AM
E&R Dept., ITLInfosys

21. Break
1/14/2019 9:43 AM
E&R Dept., ITLInfosys

22. COPY Verb
The COPY is executed at compile time unlike other COBOL verbs which are executed at run time.
The COPY statement allows programs to include frequently used source code text from a copy file or a copy library.
The COPY can include source code text with or without change into the client program.
Each client program which wants to use items described in the copy library uses the COPY verb to include the descriptions it requires.
1/14/2019 9:43 AM
E&R Dept., ITLInfosys

23. COPY Verb Examples (1) COPY “EMPLOYEE-RECORD”.
(2) COPY ”STUDENT" REPLACING ABC BY XYZ.
1/14/2019 9:43 AM
E&R Dept., ITLInfosys

24. COPY Example IDENTIFICATION DIVISION. PROGRAM-ID. COPYEG1.
AUTHOR. JYOTHI SRIDHAR.
ENVIRONMENT DIVISION.
FILE-CONTROL.
SELECT StudentFile ASSIGN TO "STUDENTS”
ORGANIZATION IS SEQUENTIAL.
DATA DIVISION.
FILE SECTION.
FD StudentFile.
COPY COPYFILE.
PROCEDURE DIVISION.
A0001-MAIN-PARA.
STOP RUN.
Copy member resides in OPERN.CICS3.COPYLIB
01 Student.
88 EndOfSF VALUE HIGH-VALUES.
02 StudentNumber PIC 9(7).
02 StudentName PIC X(60).
02 CourseCode PIC X(4).
02 FeesOwed PIC 9(4).
02 AmountPaid PIC 9(4)V99. 16

25. CALL Verb
Is the most important verb that provides structured programming capabilities in COBOL.
Is equivalent to a function or a sub-routine call in other computer languages.
Is similar to the COPY verb, in the sense that it provides code re-usability.
Provides two ways of passing parameters to the called program (1) By REFERENCE and (2) By CONTENT.
1/14/2019 9:43 AM
E&R Dept., ITLInfosys

26. Syntax of call statement
CALL NAME OF THE SUB PROGRAM
USING THE PARAMETER NAMES
Example
CALL SUBPGM1 USING NUM1,NUM2
1/14/2019 9:43 AM
E&R Dept., ITLInfosys

27. Passing by reference and value
CALL SUBPGM1 USING WS-NUM1.
BY VALUE
CALL SUBPGM1 USING
BY CONTENT WS-NUM1
BY REFERENCE WS-NUM2
BY REFERENCE WS-NUM3.
1/14/2019 9:43 AM
E&R Dept., ITLInfosys

28. Rules for coding CALLed Programs
DATA DIVISION.
WORKING –STORAGE SECTION.
----
LINKAGE SECTION.
01 WS-NUM1 PIC 9(3).
01 WS-NUM2 PIC 9(3).
PROCEDURE DIVISION USING WS-NUM1,WS-NUM2
DATA DIVISION.
WORKING –STORAGE SECTION.
----
LINKAGE SECTION.
01 WS-NUM1 PIC 9(3).
01 WS-NUM2 PIC 9(3).
The CALLed programs should have a LINKAGE SECTION in the DATA DIVISION.
If the CALLed programs possess WORKING-STORAGE SECTION, then the LINKAGE SECTION must appear after it.
The PROCEDURE DIVISION of the CALLed program must have a USING clause to identify the variables passed from the CALLing program.
1/14/2019 9:43 AM
E&R Dept., ITLInfosys

29. Rules for coding CALLed Programs
DATA DIVISION.
WORKING –STORAGE SECTION.
----
LINKAGE SECTION.
01 WS-NUM1 PIC 9(3).
01 WS-NUM2 PIC 9(3).
PROCEDURE DIVISION USING WS-NUM1,WS-NUM2.
A001-MAIN-PARA.
-----
EXIT PROGRAM
The variables defined in the LINKAGE SECTION can be defined in any order.
The variables in the USING clause must be in the same order as in the CALL statement of the CALLing program.
Instead of a STOP RUN statement, the CALLed program must contain an EXIT PROGRAM statement to transfer the control back to the CALLed program.
1/14/2019 9:43 AM
E&R Dept., ITLInfosys

30. Review Index sequential file organization. Relative file organization.
The COPY verb.
The CALL verb.
1/14/2019 9:43 AM
E&R Dept., ITLInfosys

31. Review questions DELETE statement should be followed by ( file/record)
_________
For updation and deletion, the files are to be opened in
___________________ mode
COPY statement is allowed only in the data division
( True / false )
Indicate which of the following COBOL verb does not use FROM phrase
ACCEPT
DISPLAY
PERFORM
WRITE
File name
Input-output (I-O)
1/14/2019 9:43 AM
E&R Dept., ITLInfosys

32. Review Questions
LINKAGE SECTION cannot have any value clause (True / False )
RENAMES clause cannot be used in LINKAGE SECTION (True / False )
COPY statement is executed during compile time rather then run time
( True/ False)
1/14/2019 9:43 AM
E&R Dept., ITLInfosys

33. Any Questions ????
1/14/2019 9:43 AM
E&R Dept., ITLInfosys

34. Thank you Jyothi Sridhar Kini E&R, Infosys
Mail-id:
Phone:
1/14/2019 9:43 AM
E&R Dept., ITLInfosys