DEQ is a Nap located in DMSSVT. Control is passed to SNAP in DMSSVT when a SNAP macro is
issued. SNAP fills in a PLIST with a beginning and ending address and
calls DMPEXEC. DMPEXEC dumps the specified storage along with the
registers and low storage to the printer. Control is then returned to SNAP and SNAP checks to see if any more addresses are specified. It
continues calling DMPEXEC until all the specified addresses havg been dumped to the printer. Control is then returned to the user. Except
for SDATA, PDATA, and DCB, all options of the SNAP macro are processed
normally. SDATA and PDATA are ignored. processing for the DCB option
is as follows: The DCB address specified with SNAP is used to verify
that the file associated with the DCB is open. If it is not open,
control returns to the caller with a return code of 4. If the file is
open, the FCB associated with the file is checked for a device type of DUMMY. If the device type is DUMMY, control returns to the caller with
a return code of 0 and storage is not dumped. ENQ is a Nap located in DMSSVT. FREEDBUF-SVC 57: This routine (FREEDBUF) located in DMSSVT receives controI-when-a:- l"REEDBUF macro is issued. Upon ent:ry, E'REr!DBUF sets up
the correct DSECT registers and calls the FREEtBUF routine in DMSSBD. This routine returns the dynamically obtained buffer (BDAM) specified in
the to the DCB buffer control block chain. Control is then
returned to the DHSSYT routine which returns control to the user. All
the options of FREEDBUF are supported. STAB-SVC 60: This routine (STAB) located in DMSSVT receives control when-i--STAE macro is issued. Upon entry, STAE creates, overlays or
cancels a STAE control block (SCB) as requested. Control is then
returned to the user with one of the following return codes in register
15: An SCB is successfully created, overlaid or cancelled.
The user is attempting to cancel or overlay a nonexistent SCB. 0(0) , 1 10 or pointer to next SCBI 4 (4) lexit address
8 (8) I parameter list address
12 (C) I DETACH is a Nap located in D8SSVT. CBKPT is a Nap located in DMSSVT. .. I , I -J RDJFCB-SVC 64: This routine (RDJFCB) receives control when a RDJFCB .aero-Instruction is issued. When it gets control, RDJFCB obtains the
address of the JFCB fro. the DCBEXLST field in the DCB and sets the JFCB to zero. It then reads the simulated JFCB located in C8SCB that was
produced by issuing a FILEDEF into the closed area. RDJFCB calls the STATE function program to determine if the associated file exists. If
it does, RDJFCB returns to the calling program. If the file does not eXist, RDJFCB sets a switch in the DCB to indicate this and then returns
to the calling program. RDJFCB is located in DMSSVT. All the options
of RDJFCB are supported.
2-128 IBM VM/370 System Logic and Program Determination--Volume 2
B2te: The switch set by the RDJFCB is tested by the FORTRAN object-time
direct-access handler (DIOCS) to determine whether or not a referenced
disk file exists. If it does not, DIOCS initializes the direct access
file. SYNAD-SVC 68: Located in DMSSVT, SYNAD attempts to simulate the functIons-SYNADAF and SYNADRLS. SYNADAF expansion includes an SVC 68
and a high-order byte in register 15 denoting an access method. SYNAD prepares an error message line, swap save areas and register 13
pointers. The message buffer is 120 bytes: bytes 1-50, 84-119 blank;
bytes 51-120, 1205 INPUT/OUTPUT ERROR nnn ON FILE: "dsname"; where
nnn is the CMS RDBUF/WRBUF error code. All the options of SYNAD are
supported. SYNADRLS expansion includes SVC 68 and a
register 15. The save area is returned,
returned to free storage.
high order byte of X'FF' in
and the message buffer is BACKSPACE-SiC 69: Also in DMSSVT. For a tape, a BSH command is issued a direct access data set, the CMS write and read
pointers are decremented by Control is passed to BACKSPACE in DMSSiT when a BACKSPACE macro is issued. BACKSPACE decrements tlie read
write pointer by ene and returns control to the user. No physical tape or disk adjustments are made until the next READ or WRITE macro is
issued. All the options of BACKSPACE are supported. Located in DMSSiN, this routine receives control when
a TGET or TPUT macro is issued. It is provided to support TSO service
routines needed by program products. TGET reads a terminal line; TPUT writes a terminal line. The return code is zero if the operation vas
successful and a four if an error was encountered. TCLEARQ is located in DMSSiN and causes the terminal
input .queue to be cleared via a call to DESEUF. At completion a return
is made to the user. STAX-SiC 96: Located in DMSSiT, STAX gets and chains a CMSTAXE control block-for-each STAX SiC issued with an exit routine address specified.
The chain is anchored by TAXEADDR in DMSNUC. If no exit address is
specified the most recently added CMSTAXE is cleared from the chain. If
an error occurs during STAI SVC processing, a return code of eight is
placed in register 15. The only option of STAX which may be specified is EXIT ADDRESS. See the DMSSQS prolog for description. B]ADL!BITE: OS READ and WRITE macros branch and link to DMSSBS. DMSSES branches and links to DMSSEB and, if the disks is an as disk, DMSSEB branches and link to DMSROS. See DMSSBS for description. as NOTE, POINT, and FIND (type c) macros
branch and link to entry points in DMSSCT. If the disk is an as disk, DMSSCT branches and links to DMSROS. See DMSSCT for descriptions. CBEC!: See the DMSSCT prolog for description. CMS of Operation and program Organization 2-129
Previous Page Next Page