IMS creates logs of activity that are performed during online executions. These log records are initially written to an OLDS, and then copied to the system log data set (SLDS). The log records that reflect completed operations not yet written to an OLDS is recorded on a write-ahead data set (WADS).
IMS 12 improves the functionality of IMS logging by adding Extended Format support and providing the buffer allocation beyond the 31-bit, among other improvements. The benefits of this enhancement is to increase logging rates while releasing storage in the extended common service area (ECSA).
Logs are the list of all activities:
- Work that has been done and changes that have been made
- To know about state of the system. This is you can recover in the even of failure
- IMS DB logs make recovery and restart is possible
The log records contain information about:
- When IMS starts and shuts down
- When programs start and terminate
- Changes made to the database