The below is the list of GDG parameters that used in across different projects.
The below parameters are mandatory.
NAME(entryname) Specifies the name of the GDG being defined.
LIMIT(limit) Specifies the maximum number, from 1 to 255, of GDSs that can be associated with the GDG being defined.
NOEMPTY and SCRATCH are default parameters.
EMPTY remove all GDS entries from GDG base when a new GDS is created that causes the GDG LIMIT to be exceeded.
NOEMPTY remove only the oldest GDS entry when a new GDS is created that causes GDG LIMIT to be exceeded.
EXTENDED allow up to 999 generation data sets (GDSs) to be associated with the GDG.
NOEXTENDED allow up to 255 generation data sets (GDSs) to be associated with the GDG. This is the default value.
FIFO The order is the oldest GDS defined to the newest GDS.
LIFO The order is the newest GDS defined to the oldest GDS. This is the default value.
Related: Difference between GDG generation(+1) Vs Generation (+2).
PURGE|NOPURGE Specifies whether to override expiration dates when a generation data set (GDS) is rolled off and the SCRATCH parameter is set.
PURGE will override the expiration date and cause the VTOC entry to be deleted regardless of the expiration date.
PURGE is ignored when NOSCRATCH is specified, either explicitly or as the default.
The default NOPURGE can be changed with the Catalog parmlib member (IGGCATxx) variable GDGPURGE.
SCRATCH|NOSCRATCH Specifies what action is to be taken for a generation data set located on disk volumes when the data set is uncataloged from the GDG base as a result of EMPTY/NOEMPTY processing. For generation data sets located on tape, this parameter has no effect.
You can override the SCRATCH|NOSCRATCH attribute when issuing the DELETE command.
SCRATCHThe GDG is deleted from all disks it occupies when uncataloged from the GDG base, regardless of whether it is SMS-managed or not.
NOSCRATCHIf the data set is a non-SMS managed data set it is not removed from any of the volumes it occupies. If the data set is an SMS-managed data set it is recataloged as a non-VSAM data set in rolled-off status, and is no longer associated with the GDG base. It is not deleted from any of the SMS-managed volumes it occupies.