The MAXIMUM subparameter determines the upper limit of CSA storage for cross-memory communication of MWEs. After this amount of CSA has been used, additional MWEs cannot be stored. The average MWE is 400 bytes. The DFSMShsm default for this subparameter is 100KB (1KB equals 1024 bytes).

Limiting CSA has two potential uses in most data centers; protecting other application systems from excessive CSA use by DFSMShsm or serving as an early-warning sign of a DFSMShsm problem.