You can use the MODIFY CATALOG operator command to work with the catalog address space (CAS) and catalogs cached in the in-storage catalog or the catalog data space cache. Using MODIFY CATALOG, you can lessen the impact of catalog recovery, diagnose problems with CAS, and adjust CAS performance.

By using MODIFY CATALOG, you can remove damaged catalog control blocks from CAS without performing a system IPL. You can also remove inaccurate VVDS control blocks after a volume recovery.

You can also use this command to obtain reports on CAS and the catalog data space cache.