Warm starting IMS (or normal restart)

Use the /NRESTART command to perform a warm start or a normal restart. You can use the FORMAT parameter to format various system data sets (something you might want to do if you have reallocated any of the data sets). If you are running an IMS DB/DC or DCCTL environment, and you request reformatting of any of the message queue data sets, you must specify BLDQ on the /NRESTART command if IMS was previously shut down with either the DUMPQ or PURGE keyword specified.

If the MTO needs to dequeue transactions after a warm start, use the /DEQUEUE SUSPEND command.

If you want to reload MSDBs during restart, use the MSDBLOAD keyword on the /NRESTART command.

If IMS is enabled to use the IMSRSC repository, IMS calls Resource Manager (RM) during warm start to read the change list, if one exists, 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 system is deleted at the end of the warm start.