Updating runtime resource definitions or runtime descriptor definitions dynamically

Use the UPDATE command with the appropriate parameters to dynamically update a runtime resource definition or resource descriptor. Changes to resource definitions or runtime descriptor definitions made by using the UPDATE command exist until the next IMS cold start, unless they are modified by another UPDATE command or the runtime resource definition or runtime descriptor definition is deleted by using the DELETE command.

Updates to runtime resource definitions and runtime descriptor definitions are recoverable across an IMS warm start or an emergency restart. Updates to resources and runtime descriptor definitions are lost if an IMS system is cold started, unless the resource and descriptor definitions were previously exported to the resource definition data set while IMS was running.

The UPDATE command can be used to update runtime descriptor definitions dynamically without having to go through the online change process. The UPDATE command can only be issued through the Operations Manager API. Each resource or descriptor is updated individually. DRD does not work like the online changes where either all resources are created, updated, and deleted, or none of the resources are created, updated, or deleted.

You cannot update the attributes of runtime resource definitions that are currently in use or that have work in progress. If a resource is in use, the UPDATE command fails. To ensure the success of an UPDATE command, stop the resource and let the work complete before you issue the UPDATE command. In an IMSplex environment, the UPDATE command might succeed on some IMS systems and fail on others.

To minimize the likelihood that an update of a resource definition will fail, perform the following steps before issuing the UPDATE command:

Procedure

  1. Stop the resource
  2. Query the resource to check for work in progress
  3. Dequeue transactions with the QUEUE command
  4. Complete the work (if any)

If all of the attributes specified by an UPDATE command are already defined for a resource, IMS takes no action and returns a completion code of zero.

Except for a few resource-specific exceptions, the UPDATE command is not valid with the SET() parameter or with any of the resource descriptor parameters if DRD is not enabled in either the DFSDFxxx or the DFSCGxxx PROCLIB member.

You cannot modify resource definitions for resources that are delivered with the IMS product. For example, you cannot modify the Fast Path utility program DBF#FPU0. You can, however, use the UPDATE command to change the status of certain IMS-delivered resources. For example, you might start or stop DBF#FPU0.

You also cannot modify the runtime descriptor definitions that are delivered with the IMS product, other than to select them as your default resource descriptor for a given resource. DFSDSDB1, DFSDSPG1, DBFDSRT1, and DFSDSTR1 are examples of the descriptors delivered with the IMS product.