Creation of GDG base

• GDG base can be created using IEHPROGM (explained in JCL utilities module) or using IDCAMS utility. Nowadays IDCAMS is preferred utility for creating GDG base
• Below is an sample JCL creating GDG base using IDCAMS

  //DEPTJOB JOB A123,’STEVE’ //STEPNAME EXEC PGM=IDCAMS //SYSPRINT DD SYSOUT=* //SYSIN DD * DEFINE GDG(NAME(PAYROLL.SALARY.MONTHLY) – LIMIT(10) - NOEMPTY - SCRATCH) /* //

• DEFINE GDG statement is used to create GDG base. The parameters can be given while creating a GDG are:-
  • NAME: - GDG name can be max 35 characters long. Since the GaaaaVxx take up to 9 positions we have to keep the name limited to 35 chars or less.
  • LIMIT: - Maximum number of generations can exist at any point of time. Number can range from 1 to 255.
    Note: - NAME and LIMIT are mandatory parameters
  • EMPTY/NOEMPTY: - You can specify either of them.
    When LIMIT specified is reached:-
    • EMPTY removes(uncatalogs) all existing generations
    • NOEMPTY removes(uncatalogs) only the oldest generation of GDG
  • SCRATCH/NOSCRATCH: - You can specify either of them.
    • SCRATCH uncatalogs and deletes the generations that are not kept
    • NOSCRATCH just uncatalogs and does not physically delete the generation from disk
  • OWNER :- Used to specify owner of the GDG
  • FOR DAYS(n) / TO (DATE) :- Used to specify the retention period using FOR DAYS(N) or to specify expiration date using TO(DATE)