You can define the DFSMSrmm control data set as either an extended format (EF) or a basic format VSAM data set. Using a basic format data set for the DFSMSrmm control data set, limits the control data set size to a maximum of 4 GB. Using an EF data set enables you to use VSAM functions such as multivolume allocation, compression, or striping. EF also enables you to define a control data set that uses VSAM extended addressability (EA) to enable the control data set to grow above 4 GB. To define an EF control data set, you must include the DATACLASS keyword on the AMS DEFINE command and reference the correct data class. Refer to z/OS DFSMS Using Data Sets for more information on EF data sets, and refer to z/OS DFSMSdfp Storage Administration for information on defining data classes with DSNTYPE=EXT and EXTENDED ADDRESSABILITY=Y.

DFSMSrmm requires CONTROL access to the control data set. The control data set cannot be a SYS1.xx data set if the control data set is to be shared. Additionally, batch LSR cannot be used with the DFSMSrmm control data set.