💬 Q&A Solutions

PARM (EXEC statement):

• Limited to 100 characters
• Passed in memory to program
• Accessed via LINKAGE SECTION
• Good for small, simple parameters

SYSIN (DD statement):

• No practical size limit
• Read as a file by program
• Can contain multiple records
• Good for control cards, complex input

// PARM example
//STEP1 EXEC PGM=MYPROG,PARM='PARAM1,PARAM2'

// SYSIN example
//SYSIN DD *
CONTROL OPTION1
DATE=20231215
LIMIT=1000
/*

NULLFILE is alternate for DUMMY. //DD DD NULLFILE. Discards output, provides EOF for input. DSN=NULLFILE equivalent. No actual dataset. Useful for testing without actual files.

DD DUMMY discards output/provides EOF for input. No I/O actually performed. DUMMY, DSN=NULLFILE equivalent. Use to skip optional outputs or provide empty input. Program sees immediate EOF on read. Writes succeed but discarded.

JES2 cards start with /*. /*JOBPARM limits resources. /*ROUTE sends output. /*OUTPUT JESDS specifies JES output. /*PRIORITY sets priority. Process by JES2, not passed to job. Position after JOB card before first EXEC.