The MSS IMS functionality provides for symbolic checkpoint and restart calls and the basic checkpoint call. The symbolic checkpoint call can provide a checkpoint ID and save areas. These checkpoint ID and save areas are stored in a file named IMSLOGR.DAT and IMSLOGR.IDX. IMS Option also writes the system generated checkpoint ID to the IMS System Log file so you can specify the system checkpoint ID as the restart ID instead of the optional user specified checkpoint ID.
If a restart call indicates that a restart should take place, the save areas are restored into the program's Working-Storage. The restart's checkpoint ID can be specified in the XRST call itself or as part of the Batch Program Command used to start the batch program. All restart calls, successful or not, are logged in the IMS System Log.
An XRST call does not reposition any databases and will not restore any PCB information. Whether or not database updates were rolled back depends on whether you are using databases which support dynamic backout. IMS Option supports dynamic database backout with its Fileshare databases and with Remote IMS databases. See the Sync Point Coordination chapter in the Technical Reference for more information.
IMS Option GSAM files are not affected by checkpoint or restart calls. A checkpoint call will not affect GSAM database position. GSAM updates are committed to the data file when the update call completes.