$XABSUM_STORE

   The $XABSUM_STORE macro moves user-specified values into fields
   of the specified XABSUM. The expanded $XABSUM_STORE code executes
   at run time on a previously initialized (allocated) XABSUM, in
   contrast to the $XABSUM macro, which initializes the XABSUM at
   assembly time. The $XABSUM_STORE macro must reside in a code
   program section.

   Format

     $XABSUM_STORE  XAB=xabsum-address,

                    NXT=next-xab-address