A master catalog cannot be recovered while it is being used as a master catalog. To recover the catalog, you must first make it a user catalog.

This can be accomplished in either of two ways:

1. IPL the system using an alternate master catalog. The old master catalog should be identified as a user catalog in the alternate master catalog. After you recover the old master, you can IPL the system using the recovered catalog.
2. Recover the catalog from a shared system. The catalog is defined as a user catalog in the other system's master catalog, and could be addressed on the sharing system as a user catalog.

You can also recover the master catalog using DFSMSdss if you have a physical dump of the volume containing the master catalog.