Generation data groups

In a non-SMS environment, the entry for the data set will be removed from the GDG base, leaving the generation data set uncataloged. In either environment, DELETE causes the data set to be scratched, and its entry in the catalog to be removed. The absolute generation name is used during cleanup processing (GDGRoot.GnnnnVnn).

The definition of the GDG base determines whether a generation data set is removed from the VTOC and the catalog, when the maximum number of generations for a GDG base is reached in a job. The scheduler does not try to override these rules. You cannot restore GDGs that have rolled off the group as a result of new data sets created in the failing job. Cleanup can only reset the catalog; it cannot recover data that has been deleted.

When specifying operation details for a job that has GDG, you can decide whether or not to use expanded JCL. At job or step restart you will be able to confirm or override your choice. To decide which kind of JCL to use, see JCL used for restart and GDG resolution.