IMS DB creates logs, for all activities performed during the execution. These log-records are initially written to an OLDS, and then copied to the system log-dataset (SLDS). The log records that reflect completed operations not yet written to an OLDS is recorded on a write-ahead data set (WADS).
IMS DB 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). The key differences -Command code Vs Processing code.
List of activities that are logged:
- 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