Operand Status Description
TRUNCS=YES RECFORM=FIXBLK or TRUNC macro used for
this file. TYPEFLE =xxxxxx (INPUT, OUTPUT, or WORK). If omitted, INPUT is assumed. UPDATE=YES file or work file is to be updated. V ARBLD= (nn) Register number if RECFORM= V ARBLK and
records are built in the output area. Omit if WORKA=YES. VERIFY=YES Check disk records after they are written.
WLRERR=xxxxxxxx Name of your wrong-length record routine. WORKA=YES GET or PUT specifies work area. Omit IOREG. Required for RECFORM=SPNUNB or SPNBLK. Figure 51 (Part 4 of 4). eMS/DOS Support of DTFSD Macro
Sequential Access Method --Imperative Macros VSE Transient Routines CMS/DOS supports the following imperative macros:
Initialization macros: OPEN and OPENR Processing macros: GET, PUT, PUTR, RELSE, TRUNC, CNTRL, ERET,
and PRTOV. Note: No code is generated for the CHNG macro.
Work file macros for tape and disk: READ, WRITE, CHECK, NOTE, POINTR, POINTW, and POINTS. Completion macros: CLOSE and CLOSER CMS/DOS supports workfiles containing fixed-length unblocked records and
undefined records. Disk work files are supported as single volume, single pack
files. Normal extents and split extents are both supported. CMS/DOS simulates the VSE transients that are fetched by macro expansion or by
the LIOCS modules. These simulation routines contain enough of the transient's
function to support the DOS/VS COBOL compiler and DOS PL/I Optimizing compiler. These routines that simulate the VSE transients execute in the CMS/DOS discontiguous shared segment.
The following VSE transients are simulated by CMS/DOS. VSE Support Under eMS 409

Transient Function under eMS/DOS $$BOPEN Fetched by the VSE OPEN macro expansion or by the VSE LIOCS modules. $$BOPEN performs DTF initialization, dependent upon the
device type, to ready the file for I/O operations. At entry to $$BOPEN, register 0 points to a list of fullword addresses containing
a pointer to the DTFs. $$BOPEN checks for supported DTF types,
and initializes DTFs in accordance with the device type. In the case of
tape data files, default DLBLs with the NOCHANGE option are
issued. (The CMS STATE command is issued to verify the existence
of the input files on disk.)
If a VSAM file is being opened (Byte 20 = X'28' in the ACB), control
is passed to the VSAM OPEN routine. When opening DTFSD files
for output or DTFCP /DTFDI disk files for output, if a file exists on a CMS disk with the same filename, filetype, and filemode, the file is
erased. If a SA!vl disk file is being opened, DTF initialization is per­
formed by involving the simulated VSE OPEN routines that reside in
the CMSBAM DCSS. $$BOPNLB Fetched by COBOL Compiler Phase 00 to read the appropriate sys­
tem or private source statement library directory record and to deter­
mine whether or not active members are present for the library. $$BCLOSE Fetched by VSE CLOSE macro expansion to deactivate a file. $$BDUMP Fetched when an abnormal termination condition is encountered.
Control is not passed to a STXIT routine. CMS/DOS performs a CP dump to a virtual printer. The routine is canceled. $$BOPENR Fetched by a VSE OPENR macro expansion. The function of $$BOPENR is to relocate all DTF table address constants from the
assembled addresses to executable storage addresses. At entry to $$BOPENR, register 0 points to an assembled address constant fol­
lowed by a list of DTF addresses tables that require address modifica­
tion. $$BOPNR3 Fetched by $$BOPENR to relocate all DTF table address constants
for unit record DTFs. $$BOPNR2 Fetched by $$BOPNR3 to relocate all DTF table address constants
for DTFDI or DTFCP. $$BOSVLT Fetched via SVC 2 by the simulated VSE OPEN/CLOSE routines in
the CMSBAM DCSS. $$BOSVL T performs clean-up and transition
functions upon completion of processing by the simulated VSE rou­
tines in the CMSBAM DCSS. EXCP Support in CMS/DOS CMS/DOS simulates the EXCP (execute channel program) routines to the extent
necessary to support the LIOCS routines described in the preceding section, "VSE Supervisor and I/O Macros Supported by CMS/DOS." Because CMS/DOS uses the VSE LIOCS routines, it must simulate all I/O at the EXCP level. The EXCP simulation routines convert all the I/O that is in the CCW 410 VM/SP System Programmer's Guide