Changing the size of coupling facility lock structures

You can use the rebuild function to change the size of a lock structure by rebuilding it using a new size. If the new size is too small, then the rebuild is stopped and message IGW322I is displayed. You can then start the rebuild process again using the size recommendations displayed in message IGW322I.

You can also issue the SETXCF START command to change the size of the lock structure. Each time it connects to a CF lock structure, DFSMS uses the initial structure size specified in the CFRM policy. In each case, either the ALTER(YES) or AUTOALTER(YES) keyword is specified, indicating to MVS that this structure can be dynamically reconfigured.

To alter the size of a CF lock structure, issue the SETXCF START command, using the following format:

   SETXCF START,ALTER,STRNAME=CF_lock_structure_name,SIZE=newsize

where:

CF_lock_structure_name: Is the name of the lock structure being altered.
newsize: Is the new structure size in megabytes.
This new size can be larger or smaller than the size of the current CF lock structure, but it cannot be larger than the maximum size specified in the CFRM policy, and less than its minimum size set by the coupling facility.

MVS automatically starts the alter process in place, without disruptions to the application using the CF lock structure.

If VSAM RLS determines that the lock table space or record table space that results from the alter function will be too small for future locking activity, VSAM RLS issues message IGW322I and continues with the alter function. In this case, you must issue a new alter using the size recommendations displayed in message IGW322I.

The alter function does not cross CF boundaries and does not take the place of the rebuild function. If you require a larger structure size than that specified in the CFRM policy, you must activate a new CFRM policy and rebuild the structure. The alter function changes the lock structure in place; you can use the rebuild function to move a lock structure to another CF.