Update Region Size on Mainframe ( z/OS )

This article details two methods of updating the "region size" on the mainframe ( z/OS ) platform.

A common system ABEND when executing ACR jobs within Mainframe ( z/OS ) environments is "S878". This typically stems from region allocations being too low for the JCL or job submitted. Increasing this value can be performed easily through one of the following two methods.

   Method #1

Depending on the method utilized to access your LPAR, there will be a screen similar to the following :

The "Size" parameter is the first location where "region size" may be defined. Please note, the largest possible value at this location is 2096128.

   Method #2

When submitting JCL, you will have a "job card" placed within the first couple lines. This should appear similar to the following :

The "REGION=" parameter is the second location where "region size" may be defined. A value of "REGION=0M" will allow you to pull as much region memory as required to complete the JCL / job submitted. This may or may not be advised depending on your site standards.

Please note, system administrators may have a system / user limit on how high these values may be set. If increased passed the defined threshold, updates to the parameter will have no effect. Please contact your system administrator for the corresponding LPAR to verify what the aforementioned threshold may be.