When DFSMShsm is running in a multiple DFSMShsm host environment with GRS (or a similar global enqueue product) installed, the method that DFSMShsm uses to serialize its control data sets depends on the CDSQ and CDSR keywords specified in the DFSMShsm startup procedure.

These keywords direct DFSMShsm to enable global enqueue serialization with GRS, to serialize the control data sets by reserving the volumes on which the control data sets reside, or to serialize the control data sets by VSAM RLS.