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3.2. Common Bank Call Using I$BJ
SYSLIB Access Methods
The I$BJ calling sequence is the preferred method of calling the SYSLIB common bank
routines. For the SYSLIB routines with a calling procedure, this is the type of call that is
generated when the calling program sets the parameter on the call to access the
common bank version of the routine. This method provides a much more flexible means
of using the SYSLIB routines than the Auto Switch method or explicitly coding an LIJ
instruction, and it retains all the advantages associated with using the common bank
version of the routines. That is, the calling program remains small because the SYSLIB
routines do not become an actual part of the calling program absolute. In addition, the
calling program will automatically reference new versions of the SYSLIB routines as they
are installed without the need for the calling program to be recompiled or re-collected.
Another advantage to using the I$BJ calling sequence is that the calling program can
switch between using the common bank version of the routines and the relocatable
version of the routines by re-collecting the program with the proper collector EQU
directives. A recompilation of the calling program is unnecessary; only a recollection is
needed. For example, if the following call to the MFDSP$ routine were in a program, the
common bank version of the MFDSP$ routine would be used.
M$FDSP,'CB' PKTLENGTH,PKTADDR,FUNCCODE
To force the program to use the relocatable version of the MFDSP$ routine, it would only
be necessary to re-collect the program with the following Collector directives included:
IN MFDSP$
EQU CBMFDSP$/MFDSP$
The Collector directive EQU forces the tag CBMFDSP$ to be evaluated as MFDSP$. An
explicit inclusion of the element that contains the entry point MFDSP$ (in this case the
element name is MFDSP$) is necessary to avoid errors during the collection. Appendix
E lists the names of all the common banks and relocatable entry points and the names of
the SYSLIB elements that include them. After the collection, the SYSLIB routine
MFDSP$ is an integral part of the new absolute program. This adds about 1,000 words
to the size of the absolute element.
Programs that originally call the relocatable version of a SYSLIB routine, for example
I$BJ X11,RFTI$ . BSP$, read file table index
and that wish to call the common bank version of the routine need the following
collector directives:
IN CBEP$$SYSLIB
EQU RFTI$/CBRFTI$
The Collector directive EQU forces the tag RFTI$ to be evaluated as CBRFTI$. The
explicit inclusion of the element CBEP$$SYSLIB is necessary to resolve the reference to
CBRFTI$. The element CBEP$$SYSLIB contains all the common bank entry point names
and must be explicitly included in collections that use the EQU directive to switch from
the relocatable version of a SYSLIB routine to the common bank version of the routine.
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