This example modifies the attributes of a generation data group. Because the attributes are cataloged in the generation data group's base catalog entry, only this entry is modified.

//ALTER3   JOB   ...
//STEP1    EXEC  PGM=IDCAMS
//SYSPRINT DD    SYSOUT=A
//SYSIN    DD    *
     ALTER -
           GDG01 -
           NOEMPTY -
           SCRATCH
/*

The ALTER command modifies some of the attributes of generation data group GDG01. The new attributes override any previously used for the GDG. Its parameters are:

• GDG01 identifies the object to be modified.
• NOEMPTY uncatalogs only the oldest generation data set when the maximum number of cataloged generation data sets is exceeded.
• SCRATCH removes the generation data set's DSCB from the volume VTOC when the data set is uncataloged. If the data set is SMS-managed, the NVR is also removed.