Emergency restarts and dynamic resource definition

IMS systems that use dynamic resource definition automatically recover the resources and runtime descriptor definitions during emergency restart by processing the checkpoint records and X'22' log records during an emergency restart, unless the COLDSYS parameter is specified for the /ERESTART command.

If IMS is enabled to use the repository, IMS calls Resource Manager (RM) at the end of emergency restart to read the change list for the IMS. The IMS change list is maintained by RM and is built if the IMPORT command with the SCOPE(ALL) keyword is issued while the IMS is down.

If a change list exists for the IMS that is being restarted, the database, program, transaction, and routing code resources and descriptors in the IMS change list and that apply to the IMS environment are quiesced and are not available for use until the stored resource definitions are imported from the repository.

After the IMS log is processed, IMS imports the stored resource definitions from the repository for the database, program, transaction, and routing code resources and descriptors in the IMS change list. It then applies the changes to the runtime resource and descriptor definitions in the IMS.

For the resources or descriptors that are in the IMS change list and that do not exist in IMS, the runtime resource definitions are created from the stored resource definitions in the repository. For the resource or descriptors that exist in IMS, the runtime resource definitions are updated with the stored resource definitions from the repository. The change list for the IMS is deleted at the end of the emergency restart.

If the COLDSYS parameter is specified, the resource definitions are read from the resource definition data set (RDDS) or the IMSRSC repository.

If IMS is enabled to use the IMSRSC repository, the change list for the IMS, if one exists, is deleted at the end of COLDSYS processing.