Specifying the amount of common service area storage

Common Service Area (CSA) storage is cross-memory storage (accessible to any address space in the system) for management work elements (MWEs). The SETSYS CSALIMITS command determines the amount of common service area (CSA) storage that DFSMShsm is allowed for its management work elements. The subparameters of the CSALIMITS parameter specify how CSA is divided among the MWEs issued to DFSMShsm. Unless almost all of DFSMShsm’s workload is initiated from an external source, the defaults are satisfactory. Figure 1 specifies the same values as the defaults.

One MWE is generated for each request for service that is issued to DFSMShsm. Requests for service that generate MWEs include:

Batch jobs that need migrated data sets
Both authorized and nonauthorized DFSMShsm commands including TSO requests to migrate, recall, and back up data sets

Two types of MWEs can be issued: wait and nowait. A WAIT MWE remains in CSA until DFSMShsm finishes acting on the request. A NOWAIT MWE remains in CSA under control of the MWE subparameter until DFSMShsm accepts it for processing. The NOWAIT MWE is then purged from CSA unless the MWE subparameter of CSALIMITS specifies that some number of NOWAIT MWEs are to be retained in CSA.

Note: If you are running more than one DFSMShsm host in a z/OS image, the CSALIMITS values used are those associated with the host with HOSTMODE=MAIN. Any CSALIMITS values specified for an AUX host are ignored.