Objectives:
CICS VR RCDS report utility DWWGJCDS and archive utility DWWAR utilizes below-the-line storage to handle requests. As the available memory in below-the-line storage is restricted to 16MB, these utilities can only process a limited number of records. When a large volume of records was processed, DWWGJCDS and DWWAR utilities were failing with S878 abend due to storage outage.
Some Terminology
1. A program running on z/OS and the zSeries mainframe can run with 24-, 31-, or 64-bit addressing (and can switch among these if needed). To address the high virtual storage available with the 64-bit architecture, the program uses 64-bit-specific instructions and must run in 64-bit addressing mode (AMODE (64)). Although the architecture introduces the unique 64-bit instructions, the program can use both 31-bit and 64-bit instructions as needed. In z/OS terminology:
1. 24-bit storage (up to 16M) is known as below-the-line storage.
2. 31-bit storage (16M to 2 GB) is known as above-the-line storage.
3. 64-bit storage (2 GB to 16 EB) is known as above-the-bar storage
2. z/OS sets memory limit based on the values of the REGION and MEMLIMIT parameters specified for the job, but the several installation exits can be used to override the limits, such as IEFUJV, IEFUSI, IEALIMIT, JES2 Exit 6 or JES3 Exit LATUX03. When a GETMAIN request is made, it must be satisfied within the available limits, that is contiguous free space within the limits must be available or the request will fail.
Changes Needed to Handle the Situation
Ø An additional (optional) parameter ALL31 in DWWIN (input DD statement) was introduced to carve memory in any line storage i.e., up to 2GB. So, the CICS VR RCDS report utility (DWWGJCDS) and archive utility (DWWAR) will be able to handle enormous number of records.
Ø ALL31: This is an optional parameter that allows the report generation utility to use storage up to the bar i.e., up to 2GB. Recommend using this parameter to avoid storage abends.
Sample1:
RCDS utility (DWWGJCDS) supports ALL31 as an optional parameter in DWWIN input DD statement to carve memory up to 2GB in order to handle the enormous records and help to avoid the storage abends.
Sample2:
Archive utility (DWWAR) ALL31 as an optional parameter in DWWIN input DD statement to carve memory up to 2GB in order to handle the enormous records and help to avoid the storage abends.
Reference links:
1. https://www.ibm.com/docs/en/cics-ts/5.6.0?topic=basics-24-bit-31-bit-64-bit-addressing
2. https://www.ibm.com/docs/en/cvrfz/6.1.0?topic=sullsus-setting-up-scan-utility-run-as-batch-job
3. https://www.ibm.com/docs/en/cvrfz/6.1.0?topic=commands-rcds-create-rcds-report
Author
Anitha Madhavan
Senior Software Engineer II