Recovery of changed runtime resource and descriptor definitions

Changes that are made to resource and descriptor definitions by using type-2 commands are logged and recoverable across a warm or emergency restart.

The runtime resource and descriptor definitions are restored from the logs during restart processing. Existing runtime resource and descriptor definitions might also be updated during warm or emergency restart if definitional changes were made in the IMSRSC repository while the IMS system was down. IMS uses change lists to preserve the changes across a warm or emergency restart.

One of the external data sources in which resource and descriptor definitions are stored is a BSAM data set called a resource definition data set (RDDS). The definitions in an RDDS are in a binary format. RDDSs are not supported for MSC resources or in IMS FDBR regions.

Another of the external data sources in which resource and descriptor definitions are stored is the IMSRSC repository. The repository is not supported in IMS FDBR regions.

For changes to be recoverable across a cold start (applicable only to non-MSC resources), the changed resource and descriptor definitions must be exported to, or stored in, a repository or a resource definition data set (RDDS) before IMS terminates, and imported into IMS either:

  • During cold start with the automatic import function.
  • After IMS is up and running with the IMPORT command.
Alternatively, you can do the following tasks:
  1. Update your IMS system definition macros.
  2. Perform a system generation.
  3. Cold start IMS.
  4. Import the resource definitions from the IMS MODBLKS data set.