• DMSEIT, if the user program is used as part of an EIEC file. • DMSABN, if there are system errors or the user program abnormally
terminates.
After DOS VSAM processing completes, DMSVSR is called by DMSDOS. DMSVSR issues an SVC 2 to execute the DOS transient routine $$BACLOS. $$BACLOS first checks for any OPEN VSAM files. If any are open, SVC 2 is
issued to $$BCLOSE (DMSCLS) to close the files.
If there are no open files or if all ACB's have been closed, $$BACLCS issues SVC 2 to $$BEOJ4, an entry point in DMSVSR. At $$BEOJ4, a PURGESYS DIAGNOSE 64 is issued to purge the CMSVSA! DCSS. DMSVSR then
checks to see if an os program has completed processing. If this is the
case, the SET DOS OFF command is issued and control returns to the
caller. OS Simulation by eMS When in a CMS environment, a processor or a user-written program is
executing and utilizing oS-type functions, as is not controlling this
action, CMS is in control. Consequently, it is not as code that is in CMS, but routines to simulate, in terms of CMS, certain OS functions
essential to the support of OS language processors and their generated
code.
These functions are simulated to yield the same results as seen from the processing program, as specified by OS Frogram logic manuals.
However, they are supported only to the extent stated in CMS documentation and to the extent necessary to successfully execute OS language processors. The user should be aware that restrictions to CS functions as viewed from OS exist in CMS. Certain TSO Service routines are provided to allow the Program Products to run under CMS. The routines are the Command Scan and Parse Service Routines and the Terminal I/O Service Routines. In addition the
user must provide some initialization as documented in TSO TMP Service Routine initialization. The OS functions that CftS simulates are shown
in Figure 22. TSO macros that support the use of the terminal monitor program (TMF) service routines are contained in TSOMAC MACLIB. The macro functions are
as described in the TSO TMP documentation with the exception of PUTLINE, GETLINE, PUTGET, and TCLEARQ.
Before using the TSO service routines, the calling program performs
the following initialization:
1. Stores the address of the command line as the first word in the
command processor parameter list (CPPL). The TSOGET macro puts the
address of the CPPL in register 1.
2. Initializes CMS storage using the STRINIT macro.
3. Clears the ECT field that contains the address of the I/O work area (ECTIOWA) • 2-122 IBM VM/370 System Logic and program Determination--Volume 2

SVC os Macro
Number Function
simulation
Routine 00 01 02 03 04 05 06 07 08 09 10 11
13
14
17
18
19 20 21
22
23 24 25
31
35 40 41
42
44
46
47
48
51
56
57 60 62
63
64
68
69
93
94
96 XDAP WAIT POST EXIT GETMAIN FREEMAIN
LINK XCTL LOAD DELETE
GET MAIN/ FREEMAIN
GET POOL TIME ABEND SPIE RESTORE ELDL/FIND OPEN CLOSE STOW OPEN.l TCLOSE DEVTYPE TRKBAL FEOV WTO/WTOR EXTRACT IDENTIFY ATTACH CHAP TTIMER STIMER DEQ SNAP ENQ F3EEDBUF STAB DETACH CHKPT RDJFCB SYNAD BACKSPACE DMSSVT DMSSVN DMSSVN DMSSLN DMSSMN DMSSMN DMSSLN DMSSLN DMSSLN DMSSLN DMSSMN Df"SSMN DMSSVT DMSSAB DMSSVT DMSSVT DMSSVT DMSSOP DMSSOP DMSSVT DMSSOP DMSSOP DMSSVT DMSSVT DMSSVT DMSSVT IJMSSVT DMSSVT DMSSVT DMSSVT DMSSVT DMSSVT DMSSVT DMSSVT DMSSVT DMSSVT DMSSVT DMSSVT DMSSVT DMSSVT DMSSVT DMSSVT GET/PUT DMSSQS READ/WRITE DMSSBS NOTE/POINT DMSSCT CHECK TGET/TPUT TCLEARQ STAX DMsscr DMSSVN DMSSVN DMSSVT -------,
Comments
Reads or writes direct access volumes for an I/O completion Posts the I/O completion
Returns from linked phase
Conditionally acquires user free
storage
Releases user-acquired free storage
Links control to another load phase
Deletes, then links control to another
load phase
Reads another lead phase into storage
Deletes a loaded phase
Manipulates free user storage Simulates an SVC10 Gets the time of day
Terminates processing
Processes program interruptions
Effective NOP Manipulates simulated partitioned data
files
Activates a data file
Deactivates a data file
Manipulates partitioned directories
Activates a data file
Temporarily deactivates a data file Obtains device-type physical
characteristics
Effective NOP Set forced EOV error code
Communicates with the terminal
Effective NOP Adds entry to loader table
Effective LINK
Effective NOP Accesses or cancels timer
Sets timer interval and timer exit
routine
Effective NOP Dumps specified storage areas
Effective NOP Releases a free storage buffer
Allows processing program to decipher
abend condition
Effective NOP Effective NOP Obtains information from FILEDEF
command
Handles data set error conditions
Backs up to the beginning of the
previous record
Manipulates data recoras
Manipulates data blocks
Accesses or changes relative track
address
Tests ECB for completion and errors
Terminal processing
Clears input queue
Adds or deletes an attention exit
level I I J
Figure 22. OS Functions that Simulates efts Method of Operation and Program Organization 2-123