Pg. of GC20-1819-2 Rev March 30, 1979 by Supp. SD23-9024-1 for 5748-XX8 Defining DOS Input and Output Files Note: This information is for VSE/VSAM users. OS/VS VSAM users should refer to the section "Defining as Input and Output Files." You must use the DLBL command to define VSAM inFut and output files for
both the AMSERV command and for program execution. The operands
required on the DLBL command are:
dlbl ddname filemode DSN datasetname (options SYSxxx where "ddname" corresponds to the FILE parametei in the AMSERV file and
"datasetname" corresponds to the entry name or filename of the VSAM file.
There are several options you can use when issuing the DLBL command
to define VSAM input and output files. These are: • VSAM, which you must use to indicate that the file is a VSAft file.
Note: You do not have to use the VSAM file if you are using any
since they imply that the file
ddnames (filenames) IJSYSCT and
being defined is a VSAM file. VSAM option to identify a file as a
of the other options listed here,
is a VSAM file. In addition, the IJSYSUC also indicate that the file • EXTENT, which you must use when you are defining a catalog or a VSAM data space; you are prompted to enter the volume information. This
option effectively provides the function of the EXTENT card in DOS/VS. • MULT, which you must use in order to access a multivolume VSAft file;
you are prompted to enter the extent information. • CAT, which you can use to identify a catalog which contains the entry
for the VSAM file you are defining. • BUFSP, which you can use to specify the size of the buffers VSAM should use during program execution. Options are entered following the open parenthesis on the DLBL command
line, with the SYSxxx: assgn sys003 e
dlbl file1 b1 dsn workfile (extent cat cat2 sys003 Additional examples using some of these options are shown below. USING VSAM CATALOGS While you are developing and testing your VSAft Frograms in CMS, you may
find it convenient to create and use your own master catalog, which may be on a CMS minidisk. VSAM catalogs, like any other cluster, can be
shared read-only among several users. You name the 'SAM master catalog for your terminal session using the
logical unit SYSCAT in the ASSGN command and the ddname IJSYSCT for the tLBL command. For example, if your VSAM master catalog is located on a nos disk you have accessed as a C-disk. you would enter: 190 IBM VM/370 eMS User's Guide

assgn syscat c
dlbl ijsysct c dsn mastcat (syscat ihen you use the ddname IJSYSCT you do not need to specify the iSAM option on the DLBL command. You must identify the master catalog at the start of every terminal
session. If you are always using the same master catalog, you might
include the ISSGB and DLBL commands in an EXEC procedure or in your PROFILE EXEC. You could also include the commands necessary to access
the DOS system residence volume and enter the CMS/DOS environment: ACCESS 350 Z SET DOS ON Z (YSAM ACCESS 555 C ISSGN SYSCIT C
DLBL IJSYSCT C DSN MASTCIT (SYSCAT PERM You should use the PERM option so that you do not have to reset the
master catalog assignment after clearing previous DLBL definitions. You must use the YSIM option on the SET DOS ON command line if you want to use any access method services function or access YSAM files.
The sample ASSGB and DLBL commands used in the above EXEC are almost
identical with those you issue to define a master catalog using A!SERV. The only difference is that you must enter the EXTENT option so that you
can list the data spaces that this .aster catalog is to control.
As an example, suppose that you have a 30-cylinder 3330 minidisk
assigned to you to use for testing your VSAM programs under CMS. Assuming that the minidisk is in your directory at address 333, you
should first it:
access 333 d
D(333) R/i -as
If you formatted the minidisk yourself, you knew what its label is. If
not, you can find out what the label is by using the CMS command:
query search
The response might be: USR191 DOS333 SYS190 SYS19E 191 A
333 C
190 S 19E Y/S R/i
R/i -as R/O R/O Use the label DOS333 in the VOLUMES parameter in the MASTC1T AMSERV file:
DEFINE MASTERCATALOG - (NAME (MASTCAT)­ VOLUME (DOS333) - CYL (4) -
FILE (IJSYSCT) NOW, to find out what extents on the minidisk you can allocate for VSAM, use the LISTDS command with the EXTENT option: Section 10. Using Access Method services and VSA! 191