PSW-key mask (PKM)

You can specify the PKM that a PC routine is to run under. The PKM, which has meaning only for PC routines that run in problem state, defines:

The PSW key values that the PC routine can set by means of the MODESET macro or the SPKA instruction
Whether the PC routine is authorized to use the MVCK, MVCS, and MVCP instructions
Other PC routines that the PC routine can invoke

Basic PC routines and stacking PC routines can run under the user's PKM, or they can run under a PKM that provides greater authority than does the user's PKM. The EKM and PKM parameters on the ETDEF macro enable you to define the PKM the PC routine will run under.

If the user's PKM provides sufficient authority for the PC routine, use the user's PKM by omitting the EKM parameter from the ETDEF macro.

If the PC routine needs more authority than the user has, use the EKM parameter to increase the authority. You must also omit the PKM parameter or specify PKM=OR. When you specify PKM=OR or omit PKM, the system determines the PKM authority for the PC routine by ORing the caller's PKM value with the EKM value.

For a stacking PC routine only, you can decrease authority or define a new authority. You do this by defining the authority in the EKM value and specifying PKM=REPLACE. Specifying PKM=REPLACE causes the system to use the EKM value as the new PKM value for the PC routine.