Mismatch of service levels

If you use modules with mismatching service levels, you can cause unpredictable results. To be safe, do not use the LPA version of a module if it differs from the version in the CICS® libraries that you are using.

Except for DFH99SVC and except for when you use the DFHCSVCU utility program to dynamically update the CICS SVC, do not use dynamic LPA with the 8 CICS modules that must be installed in the MVS link pack area. For details about the DFHCSVCU utility program, see, Running the DFHCSVCJ job.

Load modules used from the LPA might be at a lower service level than the rest of your CICS region in any of the following circumstances:

You are running CICS from libraries that belong to a target zone currently at a higher service level than the LPA zone.
You have applied service to the LPA zone since the last IPL of MVS.
You are not using the MLPA to replace service-updated load modules, but have applied service to the LPA zone since the last IPL of MVS for which CLPA (create link pack area) was specified.

Thus, if you have applied service to a load module in your CICS libraries, you must also apply the service to the LPA version of the module, if one exists, so that the MVS link pack area always contains tested load modules.

Use the SMP/E RESTORE function to remove the USERMOD before the LPA zone is updated or copied. Then apply the USERMOD again.

If you have used a copy of the CICS-supplied USERMODs to install modules into the MVS link pack area, and the original USERMOD is serviced, you can reflect the changes in your version of the USERMOD.

Although it is possible for CICS PTFs to make changes to the CICS modules which must reside in the MVS link pack area, in reality it is a fairly rare event. The modules have to be downwardly compatible with lower releases, and applies to any code changes made to them by PTFs, as well as to the code at base level.