modifying the address field.
upon the type ofSiC call, and -- ----- all The address field modification depends
upon whether or not the called routine
ForSiC 202 and 203, the called routine indicates a normal return by
placing a zero in register 15 and an error return by placing a nonzero
code in register 15. If the called routine indicates a normal return,
thenDMSITS makes a normal return to the calling routine. If the called
routine indicates an error return,DMSITS passes the error return to the
calling routine, if one was specified, and abnormally terminates if nonewas specified.
For anSVC 202 not followed by "DC AL4(address)", a normal return is
.ade to the instruction following theSVC instruction, and an error return causes an abend. For an SVC 202 followed by "DC AL4(address)", a
normal return is made to the instruction following the DC, and an error
return is made to the address specified in the DC. In either case,
register 15 contains the return code passed back by the called routine.
For anSVC 203 with a positive halfword code, a normal return is made
to the instruction following the halfword code, and anerror return
causes an abend. For anSVC 203 with a negative halfword code, both
normal and error returns are made to the instruction following the
halfword In any case, register 15 contains the return code passed
tack by the called routine.
For macro simulationSVC, calls, and for user-handled SVC calls, no
error return is recognized byDMSITS. As a result, DMSITS always
returns to the calling routine by loading the svc oldPSi, which was
saved whenDMSITS was first entered. Upon entry to DMSITS, all registers are saved as they were when the SVC instruction was first executed. Upon exiting from DMSITS, all registers
are restored from the area in which they were saved at entry.
The exception to this is register 15 in the case ofSVC 202 and 203. Upon return to the calling routine, register 15 always contains the
value that was in register 15 when the called routine returned toDMSITS after it had completed processing.
If the called routine
storage protect key ofSave Area.
has system status, so that it runs with aPSi 0, then it may store new values into the System If the called routine wishes to modify the location to which control
is to be returned, it must modify the following fields:• For SVC 202 and 203, it must modify the NUMRET and ERRET (normal and
error return address) fields.• Fer ether SiCs, it must modify the address field of OLDPSW. To modify the registers that are to be returned to the calling routine,
the fields EGPR1, EGPR2,••• , EGPR15 must be modified.
Part 3. ConversationalMonitor System (CMS) 265
upon the type of
upon whether or not the called routine
For
placing a zero in register 15 and an error return by placing a nonzero
code in register 15. If the called routine indicates a normal return,
then
routine indicates an error return,
calling routine, if one was specified, and abnormally terminates if none
For an
.ade to the instruction following the
normal return is made to the instruction following the DC, and an error
return is made to the address specified in the DC. In either case,
register 15 contains the return code passed back by the called routine.
For an
to the instruction following the halfword code, and an
causes an abend. For an
normal and error returns are made to the instruction following the
halfword
tack by the called routine.
For macro simulation
error return is recognized by
returns to the calling routine by loading the svc old
saved when
are restored from the area in which they were saved at entry.
The exception to this is register 15 in the case of
value that was in register 15 when the called routine returned to
If the called routine
storage protect key of
has system status, so that it runs with a
is to be returned, it must modify the following fields:
error return address) fields.
the fields EGPR1, EGPR2,
Part 3. Conversational