Change use attribute installation exit (CBRUXCUA) usage requirements

The change use attribute installation exit must reside in load module CBRUXCUA. It is invoked by way of the MVS LINK macro and must reside in a library in the LNKLST concatenation. The installation exit can be executed above or below the 16-megabyte line. The installation exit must be coded and link-edited on the system as re-entrant.

Under some circumstances, CBRUXCUA may be invoked in a key other than the job key. Therefore, all storage dynamically acquired by CBRUXCUA should be obtained from subpool 227, 228, 229, 230, 231, or 241, in order to ensure that it is accessible in the program status word (PSW) key.

The following characteristics describe the execution environment in which the change use attribute installation exit is invoked:

Task mode
Unlocked
Noncross memory mode (HASN = PASN = SASN)
The addressing mode specified when the exit was linkage edited
Primary ASC mode (not AR mode)
User key, supervisor state

Mapping macro CBRUXCPL must be included by the installation exit.