mainframe jcl exec and dd statements part - 3

MAINFRAME REFRESHER JCL PART-3

( EXEC AND DD STATEMENTS )

JANAKI RAM SOMISETTY

MAINFRAMES REFRESHER PART-3 JCL

EXEC STATEMENT(EXEC) EXEC Statement is used to identify program name or

procedure name. Maximum we can code 255 EXEC statements in a

JOB. In EXEC statement has two kinds of parameters

Position parameter Keyword parameter

PGM TIME , COND PROC REGION , PARM

If you not mention any thing default it takes PROC


PGM

This is a positional parameter which must be coded after EXEC with one blank. This parameter indicates the name of program (or) procedure name

Syntax //STEPNAME EXEC PGM=REPORT (OR)

PROC = PROCEDURE NAME


PARM It is keyword parameter and it is mainly used for

passing the data to another program. To pass input to Application program To invoke complier option.

This is a keyword parameter at activity / step level must be coded with exec operand after PGM parameter.

This parameter allows MAX(100) characters. To receive PARM parameter data, Cobol program

must be coded with “Procedure Division Using Parameter ” option.

These parameters must be declared in the linkage section.


DATA DESCRIPTOR STATEMENT ( DD STMT)

It is used to identify files( input and output ) used in JCL

DD name act as a bridge b/w Cobol program and execution JCL

In DD statement has two kinds of parameters.

Position Parameter Keyword Parameter

* DSN,DISP DATA SPACE,UNIT DUMMY DCB,VOLUME


* Position parameter at DD level used with SYSIN to

pass data to Cobol programs this is known as In stream data any number of records can be passed to the program.

In stream data is used to pass values from JCL to Cobol dynamically.

To accept the values in Cobol program, we should have equivalent accept verbs.

Syntax //SYSIN DD * ------- Entry of in stream data 100 200 /* ---------------------- End of in stream data

INPUT


DATA We can pass any thing to another program including

special character Syntax

//SYSIN DD DATA100/*200/*

INPUT


DUMMY All files are treated as End of the file

Syntax

//SYSIN DD DUMMY

NOTEThere is no input to the application all input files treated as End of the file.


DSN Through DSN we can refer temporary / permanent

file Is a physical space or file where the records will be

stored.

o DISP

• DISP parameter is used to identify the mode of the file.

• DISP= ( STATUS, NORMAL , ABNORMAL )

TERMINATION TERMINATION

NEW DELETE DELETE

OLD KEEP KEEP

SHR CATLG CATLG

MOD UNCATLG UNCATLG


NEW Creating the data set first time

OLD Already created accessing the data set all resources are allocated exclusively . No other user can until is released by the current user. If dataset is not existing this creates.

SHR The data set can be accessed by multiple users at a time.

MOD Appending the records to the existing record

NOTE If the dataset is not existing , then MOD is assumed as NEW and writes records to the

dataset.


NORMAL All the parameters of normal are active when the JOB executes successfully.

DELETE Dataset is deleted when job creates successfully

KEEP It keeps dataset in system. But it doesn’t create any reference in CATLG

CATLG When job terminates successfully it is going to create an index by a referencing name

specified in volume label. This keeps data set.

UNCATLG I resides in system, but it deletes volume label name from CATLG like keep.

PASS To pass dataset to subsequence steps.


ABNORMAL

It indicates the unsuccessful execution and allowed parameters are similar to normal termination expect pass.

Default

DISP = (NEW,DELETE,DELETE)


SPACE This is a keyword parameter in DD Operand can be

coded anywhere after DD Operand . This is used to request the storage for the dataset as

per the requirement . The storage space is divided in to primary and

secondary for effective storage space utilization.

EX

Space = (TRK,(5,3,0),RLSE)

PRIMARY

SECONDARY

DIRECTORY BLOCKSTORAGE DEVICE


CYLINDERS.BLOCKS,TRACKS AND RECORDS

Different types of STORAGESo PRIMARY

o This is primary which is allocated to the data set while creating.

o SECONDARY o This is additional memory allocated in addition to

the primary memory.o RLSE

o Is used to release the unused space when PGM terminates successfully / unsuccessfully.


DATA CONTROL BLOCKS This contains the following parameters used to

specify file attributes. EX

DCB=(LRECL=100,BLKSIZE=1000,RECFM=FB,DSORG=PS)

Logical record f/fb = fixed lengthLength = 100 v/vb= variable length (PO/PS)Fixed/variable length f/fb LRECL=100

v/vb LRECL=Maxlength+4

Block size(LRECL * 10)

mainframe jcl exec and dd statements part - 3

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