Running a started task that uses catalogs

A catalog describes data set attributes and indicates the volumes on which a data set is located. Catalogs are allocated by the catalog address space (CAS), a system address space for the DFSMSdfp catalog function.

For a started task to use data sets cataloged in a catalog, either of the following must occur:

You start the started task after the CAS is fully active, or
The started task is one of the following:
- Not a subsystem
- A subsystem that is used to start another task
- A subsystem that is started under the primary JES subsystem

If neither of those conditions is met and the task attempts to obtain catalog information, the system ends the started task abnormally. To avoid this potential abend, either specify unit and volume information in your JCL for each data set cataloged in a catalog, or catalog the data sets in the master catalog.