Special DD statements

Any label can be used for the DD statements except the reserverd or special list of ddnames for special-function DD statements. The following are the list of special DD statements for specific uses

• JOBLIB
• STEPLIB
• SYSPRINT
• SYSIN
• SYSABEND
• SYSMDUMP
• SYSUDUMP

JOBLIB:

Used to identify a program library (PDS) to search first when attempting to locate load modules (PGM=) executed within the entire JOB. Must be placed after the JOB statement and before the first EXEC statement in the JOB. More than one program library can be concatenated. If a STEPLIB is specified in a JOB that also has a JOBLIB, the STEPLIB takes precedence when searching for a program

Example:

If two load modules are members of the same PDS then execute the load modules by

//PROGPUB JOB NOTIFY=USER
//JOBLIB DD DSN=,DISP=SHR
//STEP1 EXEC PGM=
//…………
//STEP2 EXEC PGM=
//…………
The OS searches the JOBLIB DSN for the two load modules.

STEPLIB:

The STEPLIB DD statement is used to identify a program library to search first when attempting to locate load modules (PGM=) executed during the JOB STEP. More than one program library can be concatenated. If a STEPLIB DD is specified in a JOB that also has a JOBLIB,the STEPLIB takes precedence when searching for a program. JOBLIB / STEPLIB is used to specify private program libraries

Example:

If two load modules are stored as members of two different PDSs, then execute the load modules by

//PROGPUB JOB NOTIFY=USER
//STEP1 EXEC PGM=
//STEPLIB DD DSN=PDS1, ……..
(where the above LM is stored)
//…………
//STEP2 EXEC PGM=
//STEPLIB DD DSN=PDS2, ……….
(where the above LM is stored)
//…………
The OS searches the respective STEPLIB DSNs for the two load modules.

SYSPRINT:

Specifies that an execution report of the load module (PGM) is required. It defines the output file containing the execution messages.

Example:

//STEP1 EXEC PGM=IEBGENER
//SYSPRINT DD SYSOUT=*
//SYSUT1……………
//

Note: 
The SYSOUT parameter specifies the output stream dataset. It routes the report to the class (device) mentioned. SYSOUT=CLASS-code, is the syntax. The class can be any alphanumeric character or an asterisk(*), which refers to the device coded in the MSGCLASS parameter of JOB statement.

SYSIN:

Used to begin an Input stream dataset; supplies data to the load module. Instream datasets begin with the parameters * or DATA in the SYSIN DD statement. 

Format:

//SYSIN DD * or DATA, or DSN

EXAMPLE:

//STEP2 EXEC PGM=LOAD1
//STEPLIB DD DSN=EMP.PDS,DISP=MOD
//SYSIN DD *
HELLO WORLD
/*

Example:

SYSABEND,SYSUDUMP,SYSMDUMP:

These are Abnormal termination dumps used to find the source of an error when a program abnormally terminates. Coded after the EXEC statement.

SYSUDUMP:

Used to request a formatted dump of the program area, including the contents of the register, a traceback of subroutines called and information about all the datasets used. The dump can be allocated to the SYSOUT CLASS, DASD or TAPE.

Syntax:

//STEP010 EXEC PGM=LM of an Application program

//SYSUDUMP DD SYSOUT=Class

SYSABEND:

Used to request a dump similar to that of SYSUDUMP and additionally the system nucleus.

SYSMDUMP:

Similar to the request of SYSABEND but the dump is unformatted.