DLBL
The OLBL command does not check the extents to see whether they are
on cylinder boundaries or whether they are entered in the proper
sequence. If you do not enter them correctly, the access method services
DEFINE function will terminate with an error. eMS assigns sequence numbers to the extents according to the order in
which they were entered. These sequence numbers are listed when you use
the LISTDS command with the EXTENT option.
In order to display the actual extents that were entered for a VSAM data set at DLBL definition time, the following commands may be entered:
DLBL (EXTENT) or QUERY DLBL EXTENT Either of these commands will provide the following information to
the user:
DDNAME The DOS filename or OS ddname. MODE The CMS disk mode identifying the disk on which the extent
resides. LOGUNIT The DOS logical unit specification (SYSxxx). This operand
will be blank for a data set defined while in CMS/OS environment; that is, the SET DOS ON command had not been
issued at DLBL definition time. EXTENT Specifies the relative starting track number and number of
tracks for each extent entered for the given dataset ddname.
If no DLBL definitions with extent information are active, the
following message is issued: DMSDLB324I NO USER DEFINED EXTENTS IN EFFECT EXTENTS: When you want to execute a program or use access method services to reference an existing multivolume VSAM data set, you must use the MULT option on the DLBL command that
identifies the file. When you use the MULT option, you are prompted to enter additional
disk mode letters, as follows:
assgn sys001 c
assgn sys002 d
assgn sys003 e
assgn sys004 f
assgn sys005 9 dlbl infile c {mult sys001 DMSDLB330R ENTER VOLUME SPECIFICATIONS: d sys002, e sys003 , f sys004 g sys005 (null line)
The above identifies a file that has extents on disks accessed at mo es
C, D, E, P, and G. These disks have been assigned to the logical un ts SYS001, SYS002, SYS003, SYS004, and SYS005. The rules for enter ng
multiple extents are: • All disks must be mounted, accessed, and assigned when you issue the
DLBL command. • You must not repeat the mode letter and logical unit of the disk that
js entered on the DLBL command line (C in the above example) . Section 2. eMS Commands 65

DLBL • If you enter they must be
ignored.
more than one mode letter and logical unit
separated by commas; trailing commas on
on a line,
a line are • maximum of nine disks may be specified you do not need to specify
them in alphabetical order. You must enter a null line to terminate the
finished entering extents; if not, an error may
reenter the entire command sequence.
command when
result and
you are
you must
In order to display the volumes on which all multivolume data sets
reside, the following commands are issued:
DLBL (MULT) or QUERY DLBL MULT The following information concerning multiple volume datasets is
provided: MODE LOGUNIT The DOS filename or OS ddname.
The CMS disk mode identifying one of the disks on which the
dataset resides.
The DOS logical unit specification (SYSxxx). This operand
will be blank for a data set defined while in CMS/OS environment; that is, the SET DOS ON command had not been
issued at OLBL definition time.
If no OLBL definitions with multiple volume specifications are
active, the following is issued: OMSOLB324I NO USER DEFINED MULTS IN EFFECT USING CATALOGS: There are two special ddnames you must use to catalog and job catalog:
IJ SYSCT IJSYSUC identifies the master catalog when you initially define it
(using AMSERV), and when you begin a terminal session. You should use the PERM option when you define it. You must assign the logical unit SYSCAT to the disk on which
the master catalog resides. If you are redefining a master
catalog that has already been identified, you may omit the SYSCAT option on the DLBL command line.
identifies a job catalog to be used for subsequent AKSERV jobs
or VSAM programs. Any programmer logical unit may be used to assign a job
catalog. Only one VSAM catalog is ever searched when a VSAM function is
performed. If a job catalog is defined, you may override it by using
the CAT option on the DLBL command for a data set. The following OLBL
command sequence illustrates the use of catalogs:
assgn syscat c
dlbl ijsysct c dsn mastcat (perm syscat
identifies the master catalog, MASTCAT, for the terminal session.
66 IBM VM/370 CMS Command and Macro Reference