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Hitting your SHRLIBRGNSIZE Limit

Troubleshooting


Problem

Receiving BPXI039I warning messages for the SHRLIBRGNSIZE limit

Symptom

*BPXI039I SYSTEM LIMIT SHRLIBRGNSIZE HAS REACHED 85% OF ITS CURRENT CAPACITY OF xxxxxxxx
*BPXI039I SYSTEM LIMIT SHRLIBRGNSIZE HAS REACHED 100% OF ITS CURRENT CAPACITY OF xxxxxxxx

Environment

Reaching your SHRLIBRGNSIZE limit is not a critical issue;  z/OS UNIX outputs the BPXI039I messages to keep the system programmer notified of what is happening with the shared library storage. Once you reach 100% SHRLIBRGNSIZE, your applications will still function. What happens is that libraries will start be loaded in the user’s private storage instead of the shared library region. The BPXPRMxx SHRLIBRGNSIZE parameter is described more fully in  this link and a more general overview of shared library processing can be found in the z/OS UNIX System Services Planning Guide in the section titled "Using the Shared Library Extended Attribute". 

We do not recommend any specific limit setting, as it is system-needs dependent. Only you can know whats best for your system.

Diagnosing The Problem

There is a tool (WJSIGSHL) that is available on GitHub that can show what modules are loaded in the shared library region. More information about this tool can be found here. Please note the disclaimer about using the z/OS Tools & Toys, documented here under the README section. Using this tool's output, you can figure out the main users of the region on your own.

Resolving The Problem

The shared library region is located in high private storage, therefore increasing SHRLIBRGNSIZE will consume high private storage. If you're looking to increase the limit, it is best to increase SHRLIBRGNSIZE in smaller increments instead of making a large jump in size to avoid any storage issues. It is recommended to set a SHRLIBRGNSIZE limit that will be about 80% - 85% used. Once it reaches 85%, z/OS UNIX will start to load libraries into user storage to help conserve space in the shared library region. Keeping the usage to 85% or below will maximize the shared library benefit. You can issue the command D OMVS,L to display the library statistics and monitor usage.

Document Location

Worldwide

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Document Information

Modified date:
26 December 2024

UID

ibm17179857

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