Changing the Master Catalog with a CAS Restart
When maintenance activities must be performed against the master catalog or it becomes damaged, the master catalog can be changed to an alternate master catalog by restarting the Catalog Address Space and specifying the alternate master catalog name on the MODIFY CATALOG,RESTART command. Careful preparation must be taken when changing the master catalog. For instructions on creating an alternate master, see Creating and Using an Alternate Master Catalog.
Note: This is temporary until the next Catalog RESTART with a different master catalog or an IPL takes place, unless the SYSCATxx/LOADxx member is changed to specify the alternate master catalog name.
Note: During IPL processing, the master catalog is allocated to the MASTER address space. If the master catalog is changed with a CAS RESTART, it only affects CAS and does not affect any other existing allocations of the master catalog, including the allocation in the MASTER address space. The master catalog remains allocated to the MASTER address space and the volume it resides on will continue to have an allocated data set on that volume. There is no way to have the MASTER address space unallocate the original master catalog.