Change accumulation using IMS HP Change Accumulation Utility

In the IMS world, change accumulation is the process of creating a compacted version of one or more IMS log data sets by eliminating records that are not related to recovery, and by merging multiple changes to a single segment into a single change.

IMS Change Accumulation utility (IMS/CA) has the following limitations:

• IMS/CA is sequential and can process only one CAGRP.
• The input logs (SLDS, RLDS, and OLDS) must be read for each change accumulation operation (repeated I/O).

When you use DFSUCUM0 of IMS/CA to build multiple change accumulation data sets from the same IMS logs, you must process in sequence as many jobs or job steps as there are change accumulation data sets.

IMS HP Change Accumulation Utility augments the existing IMS/CA process by providing an environment in which DFSUCUM0 processes run in parallel. IMS HP Change Accumulation Utility creates multiple tasks in a single address space for reading the input log data sets and multiple z/OS® address spaces for creating the new change accumulation data sets.

In an IMS environment with multiple systems, you can run IMS HP Change Accumulation Utility simultaneously for all systems.

IMS HP Change Accumulation Utility allows multiple CAGRPs to be processed while reading the input logs in one pass. This capability saves I/O and CPU resources and time.

Additionally, IMS HP Change Accumulation Utility enables multiple CAGRPs to be processed in parallel by submitting subordinate address spaces with each running change accumulation for a single CAGRP.

Optionally, IMS HP Change Accumulation Utility enables multiple CAGRPs to be processed as separate sub-tasks in a single address space.

In summary, IMS HP Change Accumulation Utility provides the following benefits:

• Schedules log and sort tasks
• Reads log files
• Routes log and control information to the started processes
• Reports activity for all tasks in a single consolidated report file