listds d (free
The response from LISTDS might look like this: FREESPACE INFORMATION FOR 'D' DISK: CYL-HD(RELTRK) TO CYL-HD(RELTRK) TRACKS 000 01 1 000 09 9 9 000 11 11 029 18 569 560 From this response, you can see that the volume table of contents (VTOe) is located on the first cylinder, so you can allocate cylinders 1
through 29 for VSAM: assgn syscat c
dlbl ijsysct c dsn mastcat (syscat perm extent DMSDLB331R ENTER EXTENT SPECIFICATIONS: 19 551
(null line)
After entering the extents, in tracks, g1v1ng the relative track number
of the first track to be allocated followed by the number of tracks, you must enter a null line to complete the command. A null line is required
because, when you enter multiple extents, entries may be placed on more
than one line. If you do not enter a null line, the next line you enter
causes an error, and you must re-enter all of the extent information.
Note that, as in DOS/VS, the extents must be on cylinder boundaries, and
you cannot allocate cylinder O. Now you can issue the AMSERV command:
amserv mastcat A ready message with no return code indicates that the master catalog is
defined. You do not need to reissue the ASSGN and DLBL commands in order
to use the master catalog for additional A!SERV functions. You can use the AMSERf command to define private catalogs and spaces for
them, also. The procedures for determining what space you can allocate
are the same as those outlined in the example of defining a master
catalog.
For a user catalog, you may use any programmer logical unit, and any
ddname:
access 199 e
listds e (free aS5gn sys001 e
dlbl cat1 e dsn private cat1 (sy5001 extent perm
amserv usercat
192 IBM VM/370 CMS User's Guide

The file USERCAT AMSERV might contain the following:
DEFINE USERCATALOG - (NAME (PRIVATE.CAT1) -
FILE (IJSYSUC)- CIL (4) - VOLUME (DOSVS2) -
CATALOG (MASTCAT) After this AMSERV command has completed successfully you can use the
catalog PRIVATE.CAT1. When you issue a DLBL command to identify a
cluster or data set cataloged in this catalog, you must identify the
catalog using the CAT option on the DLBL command for the file:
assgn sys100 c
dlbl file2 e dsn ? (sys100 cat cat1 Or, you can define this catalog as a job catalog.
If you want to set up a user catalog as a job catalog so that it will be
searched during all subsequent jobs, you can define the catalog using
the special ddname IJSYSUC. For example:
assgn sys101 c
dlbl ijsysuc c dsn private cat1 (sysl0l perm
If you defined a user catalog (IJSYSUC) for a terminal session dllU you use the AMSERV command to access a VSAM file, the user catalog takes
precedence over the master catalogc This means that for files that
already exist, only the user catalog is searched. When you define a
cluster, it is cataloged in the user catalog, rather than in the master
catalog, unless you use the CAT option to override it.
If you want to use additional catalogs during a terminal session, you
first define them just as you would any other VSAM file:
assgn sys010 f dlbl mycat2 f dsn private cat2 (sysOl0 vsam
Then, when you enter the DLBL command for the VSAM file that is
cataloged in PRIVATE.CAT2 use the CAT option to refer to the ddname of
the catalog:
assgn sysOl1 f
dlbl input f dsn input file (sysOll cat mycat2
If you want to stop using a job catalog defined as IJSYSUC, you can
clear it using the CLEAR option of the DLBL command:
dlbl ijsysuc clear
Then, the master catalog becomes the job catalog for files not defined
with the CAT option. Section Using Access Method Services and VSAM 193