Add Master Catalog enqueue (or something) to prevent unexpected master catalog delete

We roll out maintenance through a rolling IPL process. Each maintenance IPL uses a rotating cycle of 2 or 3 sysres sets (call them A, B and possibly C), of which the oldest is built with the new maintenance each time.

Part of this process is to also build a new master catalog, which will be brought in with the IPL; we therefore have a cycle of 2 or 3 rotating master catalogs (call them A, B and possibly C), kept in sequence with the sysres. When IPLing from sysres A, we use master catalog A.

The to-be master catalog is copied from the current master catalog, and updates applied to the to-be one so we can add new datasets, change volumes, delete what will be redundant ones and so on without affecting the running system.

We need the to-be master catalog connected as a user catalog to the active master catalog to be able to perform this and other maintenance (such as ensuring that new aliases are defined to both active and to-be).

This means that at a given point throughout our roll-out, some systems in a sysplex that share the master catalog can be using a different master catalog to others.

It is not possible to delete the active master catalog on a given system, but it is possible to delete a user catalog that is being used as a master catalog on another system.

There should be some way of preventing this, such as a shared enqueue on the master catalog, because once the master catalog has been deleted, it is not long before the system or systems that were using it fail.

This would enhance system stability and prevent errors by more junior members of staff who may not realise where a master catalog is being used.