eMS/DOS Planning Considerations for CMS/DOS Installations that use eMS/DOS must also have available a DOS/VS system
(Release 31 and above). Therefore, if you want to use CMS/DOS you must
first order and install a DOS/VS system. Also, if you want to use the DOS/VS COBOL and DOS PL/I compilers under CMS/DOS, you must order them
and install them on your DOS/VS system. DOS/VS System Generation Considerations
The CMS/DOS support in CMS uses a real DOS/VS system pack in read-only
mode. CMS/DOS provides the necessary interface and then fetches DOS/VS logical transients and system routines directly from the DOS/VS system
libraries. Also, CMS/DOS fetches the DOS/VS COBOL and DOS PL/I compilers directly from the DOS/VS system or private core image
libraries.
It is your responsibility to order the DOS/VS system and then
generate it. Also, if you plan to use DOS compilers, you must order the DOS/VS COBOL and DOS PL/I Optimizing compilers and install them on the
same DOS/VS system. When you install the compilers on
link-edit all the compiler relocatable
linkage editor control statement: ACTION REL
the DOS/VS system,
modules using the
you must
following You can place the link-edited phases in either the system or the private
core image library. When you later invoke the compilers from eMS/DOS, the library (system
or private) containing the compiler phases-must be identified for CMS. You identify all the system libraries to eMS by coding the filemode
letter that corresponds to that DOS/VS system disk on the SET DOS ON command when you invoke the CMS/DOS environment. You identify a private
library by coding ASSGN and DLBL commands that describe it. These DOS/VS system and private disks must be linked to your virtual machine
and accessed before you issue the commands to identify them for CMS. CMS/DOS has no effect on the update procedures for DOS/VS, DOS/VS COBOL, or DOS PL/I. You should follow the normal update procedure for
applying IBM-distributed coding changes to them. PTFs that must be
applied are listed in the current VM/370 Release When the DOS/VS System Must Be Online Most of what you do in the CMS/DOS environment requires that the DOS/VS system pack and/or the DOS/VS private libraries be available to eMS/DOS. In general, you need these DOS/VS volumes whenever: • You use the
compilers are
libraries. DOS/VS COBOL compiler or DOS executed from the system or PL/I compiler • private core
The
image Part 1. Planning for System Generation 35

CMS/DOS • Your DOS/VS COBOL or DOS PL/I source programs contain COPY, LIBRARY, %INCLUDE, or CBL statements. These statements copy books from your
system or private source statement library. • You invoke one of the librarian programs: DSERV, RSERV, SSERV, PSERV, or ESERV. • You link-edit DOS programs that use LIOCS modules. CMS/DOS link
edits LIOCS routines with the DOS program from DOS/VS system or
private relocatable libraries. • You execute DOS programs that fetch phases directly from DOS/VS system or private core-image libraries.
A DOS/VS system pack is usable when it is: • Defined for your virtual machine • Accessed • Specified, by mode letter, on the SET DOS ON command
A DOS/VS private library is usable when it is: • Defined for your virtual machine • Accessed • Identified via ASSGN and DLBL commands
The DOS/VS system pack and private libraries may reside on full packs or
minidisks. CMS/DOS Tape Handling CMS/DOS does not process tape labels.
bypasses labels on input tapes or passes
process header labels on input tapes.
tapes as tapes with no labels. Trailer
input tapes or output tapes.
In general, CMS/DOS either
control to a user routine to CMS/DOS processes all output
labels are not supported for CMS/DOS passes control to user label routines, if there are any, for
input tapes with standard or nonstandard labels.
If a tape which is opened as an output tape already has a header
label (standard or nonstandard), CMS/DOS writes over that label when it
writes data to the tape.
There is
statement.
no equivalent in CMS/DOS to the DOS/VS TLBL
The TLBL label function is not required in CMS/DOS. Standard Label Cylinder control CMS/DOS does not support a standard label cylinder. If the real DOS/VS system pack used by CMS/DOS has a standard label cylinder, it is not
used.
In CMS/DOS, ASSGN and DLBL commands provide functions similar to
those provided by the DOS/VS ASSGN, DLBL, and EXTENT control statements.
In DOS/VS those control statements are in effect only for one job.
Thus, it is convenient to place often used DLBL and EXTENT control
statements on the standard label cylinder.
36 IBM VM/370 Planning and System Generation Guide