Question about MIMINIT PAGEFIX

Document ID : KB000012320
Last Modified Date : 14/02/2018
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Introduction:

Customer have reviewed MIM PAGEFIX description on Programming Guide.

Typically, the CA MIM for z/OS working set size remains fixed in real storage and there is no need to page fix its cell pool resident control blocks. However, in times of critical pageable storage shortages, frames can be stolen from the working set pages. If a given system is configured as such that it is real storage constrained, then you may want to prevent real frames from being taken from the CA MII address space.

They asked what exactly "in times of critical pageable storage shortages" is.

Question:

What exact value or definition on z/OS does MIM check to see critical pageable storage shortages?

Answer:

If PAGEFIX=YES, all MIM private cell-pooled storage will be page fixed.
If PAGEFIX=COND, then MIM will only page fix the storage if the MCTFX1 bit is OFF, meaning there is not a current storage shortage. This is a z/OS bit, not a MIM bit.