JCL GDG - Generation data group

 

GDG – GENERATION DATA GROUP

a concept in the mainframe that allows organizing and managing datasets or files over the time.

These are a group of datasets that are logically related (with the same attributes like format and record length) to each other from the process and usage point of view.

All datasets (generation) within GDG share the same name except the last qualifier, which is a combination of the generation number and version number.

The same name is called as "GDG Base", and the remaining datasets with a different qualifier at the end are called as "GDG Files or GDG Generations".

At any point, a GDG can have a maximum of 255 generations.

CREATE A GDG BASE	CREATE A PS IN A GDG BASE OR          VERSIONS IN A GDG BASE
//STEP01    EXEC PGM=IDCAMS //SYSPRINT  DD SYSOUT=* //SYSOUT    DD SYSOUT=* //SYSIN     DD *                 DEFINE GDG ( NAME (WORK.FIRST.GDG1) –                LIMIT(3)               -                NOEMPTY                -                SCRATCH )  /* //	//STEP01    EXEC PGM=IEFBR14 //SYSPRINT  DD SYSOUT=* //SYSOUT    DD SYSOUT=* //SYSDUMP   DD SYSOUT=* //DD1       DD DSN= WORK.FIRST.GDG1(+1),                             DISP=(NEW,CATLG,DELETE),                DCB=(DSORG=PS,RECFM=FB,                LRECL=80,BLKSIZE=800),                SPACE=(TRK,(1,1),RLSE),                UNIT=SYSDA
TO ALTER A GDG BASE	TO DELETE A GDG BASE
//STEP01    EXEC PGM=IDCAMS //SYSPRINT  DD SYSOUT=* //SYSOUT    DD SYSOUT=* //SYSIN     DD *                 ALTER WORK.FIRST.GDG1 LIMIT(10) /*	//STEP01    EXEC PGM=IDCAMS //SYSPRINT  DD SYSOUT=* //SYSOUT    DD SYSOUT=* //SYSIN     DD *                 DELETE WORK.FIRST.GDG1 FORCE /*
TO DELETE A GDG CURRENT VERSION	TO DELETE A GDG PREVIOUS VERSION
//STEP01    EXEC PGM=IEFBR14 //SYSPRINT  DD SYSOUT=* //SYSOUT    DD SYSOUT=* //SYSDUMP   DD SYSOUT=* //DD1       DD DSN=WORK.FIRST.GDG1(0),                DISP=(OLD,DELETE,DELETE)	//STEP01    EXEC PGM=IEFBR14 //SYSPRINT  DD SYSOUT=* //SYSOUT    DD SYSOUT=* //SYSDUMP   DD SYSOUT=* //DD1       DD DSN=WORK.FIRST.GDG1(-5),                DISP=(OLD,DELETE,DELETE)

 

COPY PS TO GDG GENERATIONS

COPY PS TO PREVIOUS VERSION IN GDG

//STEP01    EXEC PGM=IEBGENER //SYSPRINT  DD SYSOUT=* //SYSOUT    DD SYSOUT=* //SYSDUMP   DD SYSOUT=* //SYSUT1    DD DSN= WORK.FIRST.FILE1,DISP=SHR              //SYSUT2    DD DSN= WORK.FIRST.GDG1(+1),                               DISP=(NEW,CATLG,DELETE),                DCB=(DSORG=PS,RECFM=FB,                LRECL=80,BLKSIZE=800),                SPACE=(TRK,(1,1),RLSE),                UNIT=SYSDA //SYSIN     DD DUMMY

//STEP01    EXEC PGM=IEBGENER //SYSPRINT  DD SYSOUT=* //SYSOUT    DD SYSOUT=* //SYSDUMP   DD SYSOUT=* //SYSUT1    DD DSN= WORK.FIRST.FILE1,                DISP=SHR              //SYSUT2    DD DSN= WORK.FIRST.GDG1(-1),                 DISP=SHR            //SYSIN     DD DUMMY   OR to current version //SYSUT2    DD DSN= WORK.FIRST.GDG1(0),