VSAM considerations for the control data sets

The three control data sets are VSAM data sets and as such need to be periodically compressed and reorganized. To redistribute records or compress the control data sets, use the Access Method Services EXPORT and IMPORT commands. To move the control data sets to another volume or to increase their space allocations, use the Access Method Services REPRO, DELETE, and DEFINE commands.

Immediately after you reorganize your control data sets you should back them up.