Defining the main coupling facility lock structure

VSAM RLS support requires the coupling facility to define a main lock structure, IGWLOCK00, for cross-system locking. You can also optionally create up to 256 secondary lock sets per sysplex.

See the z/OS DFSMSdfp Storage Administration Reference manual for information about calculating the size you require for the lock structure.

The amount of coupling facility space required depends on several characteristics of your hardware configuration and the applications that you run:
  • The number of processors you have
  • The power of your processors
  • Your ratio of nonupdate activity to update activity
  • Your ratio of recoverable updates to nonrecoverable updates
  • Your ratio of sequential requests to direct requests

You define the lock structure in the CFRM policy with the IXCMIAPU utility.

As of z/OS® 2.1, up to 256 secondary lock sets can be created in addition to the primary IGWLOCK00. Using a secondary lock structure can prevent workloads interfering with each other and improve system and application availability. Secondary lock structures help prevent locking constraints and allow isolation of workloads.