Adjusting VSAM options specified in the Access Method Services DEFINE CLUSTER command

To adjust these VSAM options, change the appropriate parameters in the DEFINE CLUSTER command. What additional things you must do depends on which VSAM parameter you are changing.

Changing the FREESPACE parameter

You can use the reorganization utilities to change the use of free space or to change the percent of free space you have specified. To make this change:

  1. Unload your database using the existing DBD and the appropriate unload utility.
  2. Recalculate database space. You need to do this because the change you are making will result in different requirements for database space.
  3. Delete the old database cluster and define the new database cluster with a change to the FREESPACE parameter.
  4. Reload your database, using either the existing DBD (if no changes were made to the DBD) or the new DBD. Use the appropriate reload utility.
  5. If the database being reorganized is a secondary index with direct pointers, you must run some of the reorganization utilities before and after reloading to resolve prefix information.

Changing the SPEED / RECOVERY parameter

Do not unload and reload your database merely to change the SPEED/RECOVERY parameter. Rather, if you have RECOVERY specified, change the parameter to SPEED to improve performance when the database is reloaded and restart of the load program is not used. IMS does not support the RECOVERY parameter. Recovery can only be done when the database load program is run under control of UCF.

Because it is assumed you would only change the parameter when making other database changes that require you to unload and reload your database, no procedure for changing it is provided here.