Pg. of GC20-1819-2 Rev March 30, 1979 by Supp. SD23-9024-1 for 5748-118 • The CMS/DOS restriction on writing to sequential files applies to SHSAM and HSAM. • To assemble a DBD or PSB under CMS/DOS, you must first copy the
DBDGEN and PSBGEN macros from the DOS/VSE source statement library to
a CMS MACLIB. For more information about using DL/I in the eMS/DOS environment, see Using DOS Files on DOS Disks You can have DOS disks attached to your virtual machine by a directory
entry or you can link to a DOS disk with the LINK command. You can use
the ACCESS command to assign a mode letter to the disk:
access 155 b
and the RELEASE command to release it:
release b
Except for VSAM disks, you cannot write on DOS disks, or update DOS files on them. You can, however, execute programs and CMS/DOS commands
that read from these files, and you can use the LISTDS command to
display the file-ids of files on a DOS disk; for example:
listds b You can also verify the existence of a particular file. For example, if
the file-id is NEW.TEST.DATA you can enter:
listds new test data b You can use this form only if the file-id has one-to eight-character
qualifiers separated by periods. If the file-id of the DOS file you
want to verify contains embedded blanks, for example NEW.TEST DATA, then
you have to enter the LISTDS commands with a question mark:
listds ? b CMS responds:
ENTER DATA SET NAME: and you can enter the exact file-id:
new. test data
If the data set exists, you receive a response: FM DATA SET NAME
B NEW.TEST DATA READING DOS FILES Under CMS/DOS, you can execute programs that read DOS sequential (Sle) files; you can also execute programs that read and write VSAM files. You cannot, however, execute programs to read direct (DAM) or indexed
sequential (ISAM) DOS files.
154 IBM VM/370 CMS User's Guide

March 30, 1979
Complete information on using CMS to access and manipulate VSAM files
is described in "Section 10. Using Access Method Services and VSAM In CMS and CMS/DOS." The discussion below lists the restrictions placed on
reading SAM files. CMS cannot read DOS files that: • Have the input security indicator on. • Contain more than 16 user labels and/or data extents. (If the file • has user labels, they occupy the first extent; therefore the file
must contain no more than 15 data extents.)
Are multivolume files.
files. End of volume
end-af-volume switching.
Multivolume files are read as single-volume
is treated as end of file. There is no • Have user labels. User labels in user-labeled files are bypassed. CMS does net support duplicate volume labels; you cannot access more
than one volume with the same six-character label while you are using CREATING CMS FILES FROM DOS LIBRARIES You can create CMS files from existing DOS files on DOS disks. simulates the DOS librarian functions DSERV, RSERV, SSERV, ESERV, and PSERV with commands of the same names; you can use these CMS/DOS commands to create CMS files from relocatable, source statement, or
procedure libraries located either on the DOS system residence volume or
in private libraries. The functions are fully described later in this
section.
If you want to create CMS files from DOS files that are not cataloged in
libraries or from DOS files on tape, you can use the MOVEFILE command.
The MOVEFILE command allows you to copy a file from one device to
another device of the same or a different tYFe. Before issuing the MOVEFILE command, the input and the output files must be described to CMS with the FILEDEF command.
The MOVEFILE and FILEDEF commands are described and examples are
given of how to use the. in "Section 8. Developing CS Program Under CMS." The procedures are the same for copying DOS files as for OS data
sets. You must, however, keep the following in mind: • Since DOS files on DOS disks do not contain ELKSIZE, RECFM, or LREeL
options, these options must be specified via the FILEDEF command;
otherwise, defaults of BLOCKSIZE=32760 and RECFM=U are assigned.
LRECL is not used for RECFM=U files. • If a DOS file-id does not follow OS naming conventions (that is, one­
to eight-byte qualifiers with each qualifier separated by a period; Section 9. Developing DOS Programs Under CMS 155