Page of GC20-1807-7 As Updated April 1, 1981 by TNL GN2S-0829 SI MULATION NOTES Because CMS has its own file system and is a single-user system
operating in a __ Y.irtual maGhin.e_Yit_h_JrirtJl.al_stQ_rage, _ th_e_re are certain
restrictions for the simulated OS function in CMS. For example, HIARCHY options and options that are used only by as multitasking systems are ignored by CMS. Due to the design of the CMS loader, an XCTL from the explicitly
loaded phase, followed by a LINK by succeeding phases, may cause
unpredictable results.
Listed below are descriptions of all the OS macro functions that are
simulated by CMS as seen by the programmer. Implementation and program
results that differ from those given in Inst£yctiQn§ and Services and Macro Instructions are
stated. HIARCHY options and those used--;nly by OS multitasking systems are ignored by CMS. Validity checking is not performed within the
simulation routines. The entry point name in LINK, XCTL, and LOAD (SVC 6, 7, 8) must be a member name or alias in a TXTLIB directory unless the COMPSWT is set to on. If the COMPSWT is on, SVC 6, 7, and 8 must
specify a module name. This switch is turned on and off by using the macro. See the VM/37Q £MS gng for
descriptions of all CMS user macros. XDAP-SVCO WAIT-SVC1 POST-SVC2 EXIT/RETURN =SVC3 GETMAIN-SVC4 FREEMAIN-SVCS LI liK-SVC6 Differences in Implementation
The TYPE option must be R or W; the V, I, and K
options are not The BLKREF-ADDR must point
to an item number acquired by a NOTE macro. Other options associated with V, I, or K are not supported.
All options of
waits for the
specified ECBs. WAIT are supported.
completion bit to
be WAIT routine
set in the
All options of POST are supported. POST sets a
completion code and a completion bit in the specified ECB. Post ECB, execute end of task routines, release
phase storage, unchain and free latest request block,
and restore registers depending upon whether this is
an exit or return from a linked or an attached
routine. Do not use EXIT/RETURN to exit from an
explicitly loaded phase. If EXIT/RETURN is used for
this purpose, CMS issues abend code AOA. All options of GETMAIN are supported except SP and HIARCHY, which are ignored by CMS, and LC and LU, which will result in abnormal termination if used.
GETMAIN gets blocks of free storage.
All options of FREEMAIN are supported except SP, which
is ignored by CMS, and L, which will result in
abnormal termination if used. FREEMAIN frees blocks
of storage acquired by ..
The DCB and HIARCHY options are ignored by CMS. All
other options of LINK are supported. LINK loads the
specified -program in-to storage- (if necessa-ry) a-nd
passes control to the specified entry point. Part 3. Conversational Monitor System (CMS) 273
April 1, 1981
The DCB and HIARCHY options are ignored by CKS.. All
other options of XCTL are supported. XCTL loads the
specified program into storage (if necessary) and
passes control to the specified entry point.
The DCB and HIARCHY options are ignored by CMS. All
other options of LOAD are supported. LOAD loads the specified program into storage (if necessary) and
returns the address of the specified entry point in register zero. However, if the specified entry point
is not in core when SVC 8 is issued, and the
subroutine contains VCONs that cannot be resolved
within that TXTLIB member, CMS will attempt to resolve
these references, and may return another entry point
address. To insure a correct address in register zero,
the user should bring such subroutines into core
either by the CMS LOAD/INCLUDE commands or by a VCON in the user program.
All the options of GETPOOL and FREEPOOL are supported. GETPOOL constructs a buffer pool and stores the
address of a buffer pool control block in the DCB.
FREE POOL frees a buffer pool constructed by GETPOOL. All the options of DELETE are supported. DELETE
decreases the use count by one and, if the result is
zero, frees the corresponding virtual storage. Code 4
is returned in register 15 if the phase is not found.
All the options of GETftAIN and FREEMAIN are supported
except SP and HIARCHY, which are ignored by CMS. CMS supports only the DEC parameter of the TIME macro
instruction. However, the time value that CMS returns
does not contain tenths of seconds or hundredths of
seconds: the time is expressed as HHMMSS. The completion code parameter is supported. The DUMP parameter is not. If a STAE request is outstanding,
control is given to the proper STAE routine. If a STAE routine is not outstanding, a message indicating
that an abend has occurred is printed on the terminal
along with the completion code.
All the options of SPIE are supported. The SPIE routine specifies interruption exit routines and
program interruption types that will cause the exit
routine to receive control.
The RESTORE routine in CMS is a NOP. It returns
control to the user.
BLDL is an effective NOP for LINKLIBs and JOBLIBs. For TXTLIBs and MACLIBs, item numbers are filled in
the TTR field of the BLDL list; the K, Z, and user
data fields, as described in Instructions, are set to zeros. The "alias" bit
of the C field is supported, and the remaining bits in
the C field are set to zero.
All the options of FIND are supported. FIND sets the
read/write pointer to the item number of the specified
274 IBM VM/370 System Programmer's Guide
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