Type III C lass A Program

Linkage Notes:
SVC X·CA·
pc AL4(*+4)
a. Commands that are not resident in the CMS nucleus may
also be called by the CMS SVC. but they are loaded at
hexadecimal location 12000. This is also the default load
point for user programs. Therefore, a higher load point
must be specified when the user's program is loaded. A
complete list of disk resident commands may be obtained with
a LISTF * MODULE SY" which also gi ves a rough idea of the
command size, expressed in SOO-byte records.
b. A few CMS routines may be executed only by branching.
The addresses of these programs are listed in a nucleus
module under the entry point SYSREF. SYSREF is resolved as
an EXTRN in any user program. The displacement from SYSREF
to the desired address is obtained with the CMSYSRFF macro
instruction, which generates a series of EQU statements.
The name of each nucleus routine, with a D prefixed to it,
is equated to its displacement from SYSREF in the address
list. The following example shows how to get to the SCAN
routine in the nucleus,.
USERJOB CSECT
EXTRN SYSREF
L
L
BALR
LTR
BNZ
CMSYSREF
3!,=A(SYSREF)
15.DSCAN(3)
14,15
15,15
ERR $
In the expansion of CMSYSREF, DSCAN is equated to the
displacement of the SCAN address in the SYSREF list. The
address is loaded into register 15 for the BALR. SCAN is a
routine to break up terminal line images in core into a
standard CMS parameter list. For further information on
SCAN" see the CMS Program Logic Manual.
Assembler Language Programming 215