(SYSLIB) Programming Reference Manual - Public Support Login ...

SYSLIB Access Methods
3.3. Common Bank Call Using Auto Switch Method
The Auto Switch method of referencing the common bank version of the SYSLIB
routines requires the calling program to be explicitly aware of its own addressing
structure. The program must know what banks are based and the addressing range of
each bank. To access one of the SYSLIB routines, the calling program bases the
particular SYSLIB common bank that contains the routine. (See Appendix D and
Appendix E for the list of the SYSLIB common banks, the routines that are contained in
them, and the addressing limits of the bank.) The program then executes an LMJ
instruction to the common bank entry-point address minus 1. The calling program must
ensure that none of the banks it has based overlap the SYSLIB addressing space.
The advantage to this system is that the program may force the SYSLIB common bank
to remain based so that multiple calls to routines in that bank can avoid the expense of
basing the bank again and again. When the I$BJ method of accessing the common bank
routines is used, it unbases the active bank of the calling program, bases the SYSLIB
common bank, executes the SYSLIB routine, then unbases the SYSLIB common bank
and bases the calling program once again.
The disadvantage to the Auto Switch method is that the structure of the calling program
needs to be rigidly defined. Any changes to the program must always take into
consideration what banks are based at what times and the addressing range of the
banks. For these reasons, the use of the Auto Switch method is not encouraged. The
Auto Switch calling method can only be used on systems that can base more than one
bank simultaneously using the LIJ instruction.
For the SYSLIB routines that have procedures to generate the calling code, the Auto
Switch calling sequence is generated by appropriately setting a parameter on the
procedure call.
7833 1733–004 3–5