The ARCSDEXT installation exit receives control just before DFSMShsm terminates its functional subtasks.

As with the initialization exit, the installation-reserved fields are the only fields in the MCVT record that you are allowed to change. All other fields are reserved for IBM's use and are subject to change.

All parameters passed to ARCSDEXT are located above the 16 MB line and have 31-bit addresses. You should link-edit ARCSDEXT in AMODE 31.