Optional functions specified in the POOLID, DBD, and VSRBF control statements

Options chosen during IMS initialization determine the size and structure of VSAM local shared resource pools.

In a batch environment, you specify these options in a data set with the DDNAME DFSVSAMP. In online systems, you specify these options in the IMS.PROCLIB data set with the member name DFSVSMnn.

With these options, you can enhance IMS performance by:

Defining multiple local shared resource pools
Dedicating subpools to a specific data set
Defining separate subpools for index and data components of VSAM data sets