GDG parameters

//CREGDG  JOB (12345),CLASS=A,MSGCLASS=X,NOTIFY=&SYSUID
//STEP01  EXEC PGM=IDCAMS
//SYSIN   DD  *
   DEFINE GDG(NAME(gdg-base-name) -
          LIMIT(nnn)       -
          EMPTY|NOEMPTY    -
          SCRATCH|NOSCRATCH)
/*

• DEFINE

  • The DEFINE command is used with the IDCAMS utility to create or define a new dataset

  • It's used to define the GDG base, which acts as a reference point for all related generations.

  • This base holds the properties like limit and deletion rules

• NAME (gdg-base-name)

  • This is where you specify the name of your GDG base. It's the common name that will be shared by all the generation datasets.

• LIMIT (nnn)

  • Defines the maximum number of generations that can exist under this GDG.

  • You can set any number from 1 to 255. Once the limit is reached, older generations are removed based on the options provided with EMPTY and SCRATCH

• EMPTY

  • When this option is used and the generation limit is reached, all existing generations are deleted at once when a new generation is added.

  • This is useful when you want to clear out all old data regularly

• NOEMPTY

  • With this option, only the oldest generation is deleted when a new generation is added, and the limit is reached.

  • This ensures that recent generations are still available and only the oldest one is removed

• SCRATCH

  • When a generation is deleted, it is completely removed from the system both from the catalog and from disk storage.

  • You cannot access the dataset again once it's scratched.

• NOSCRATCH

  • This option removes the dataset from the catalog only, but the file still exists on disk.

  • You can still access it later if you remember or know the exact name of the data