Using DFSMShsm Control Data Sets

DFSMShsm control data sets (CDS) are system-type data sets that DFSMShsm uses to keep track of all DFSMShsm-owned data. They consist of migration, backup, and offline control data sets. The control data sets are an inventory of low activity and inactive data that was stored by DFSMShsm and used to manage its environment. DFSMShsm logs its transactions and maintains multiple backup versions of its CDSs for recovery purposes as specified by the user.

DFSMShsm can use VSAM KSDS extended addressability (EA) capabilities that use any of the following serialization techniques for accessing its CDSs:

Record-level sharing (RLS) access mode
CDSQ serialization
CDSR serialization

VSAM EA capabilities allow each migration control data set (MCDS), backup control data set (BCDS), and offline control data set (OCDS) cluster to exceed the 4 GB size. The MCDS and BCDS can span up to four unique KSDS clusters. The OCDS is limited to a single cluster. The same serialization technique must be used to access all CDSs.