IBM OS/390 User Manual
Device Support Facilities (DSF). An IBM-supplied
system control program for performing operations on
disk volumes so that they can be accessed by IBM
and user programs. Note: Examples of these
operations are initializing a disk volume and assigning
an alternate track.
system control program for performing operations on
disk volumes so that they can be accessed by IBM
and user programs. Note: Examples of these
operations are initializing a disk volume and assigning
an alternate track.
device-independent. Pertaining to a program that
can be executed successfully without regard for the
characteristics of particular types of devices. Contrast
with device-dependent.
can be executed successfully without regard for the
characteristics of particular types of devices. Contrast
with device-dependent.
DFSMS environment. An environment that helps
automate and centralize the management of storage.
This is achieved through a combination of hardware,
software, and policies. In the DFSMS environment for
MVS, this function is provided by MVS/ESA SP and
DFSMS/MVS, DFSORT, and RACF. See also
system-managed storage.
automate and centralize the management of storage.
This is achieved through a combination of hardware,
software, and policies. In the DFSMS environment for
MVS, this function is provided by MVS/ESA SP and
DFSMS/MVS, DFSORT, and RACF. See also
system-managed storage.
DFSMSdfp. A DFSMS/MVS functional component that
provides functions for storage management, data
management, program management, device
management, and distributed data access.
provides functions for storage management, data
management, program management, device
management, and distributed data access.
DFSMSdss. A DFSMS/MVS functional component
used to copy, move, dump, and restore data sets and
volumes.
used to copy, move, dump, and restore data sets and
volumes.
DFSMShsm. A DFSMS/MVS functional component
used for backing up and recovering data, and
managing space on volumes in the storage hierarchy.
used for backing up and recovering data, and
managing space on volumes in the storage hierarchy.
DFSMShsm-managed volume. (1) A primary storage
volume, which is defined to DFSMShsm but which
does not belong to a storage group. (2) A volume in a
storage group, which is using DFSMShsm automatic
dump, migration, or backup services. Contrast with
system-managed volume and DFSMSrmm-managed
volume.
volume, which is defined to DFSMShsm but which
does not belong to a storage group. (2) A volume in a
storage group, which is using DFSMShsm automatic
dump, migration, or backup services. Contrast with
system-managed volume and DFSMSrmm-managed
volume.
DFSMShsm-owned volume. A storage volume on
which DFSMShsm stores backup versions, dump
copies, or migrated data sets.
which DFSMShsm stores backup versions, dump
copies, or migrated data sets.
DFSMS/MVS. An IBM licensed program that together
with MVS/ESA SP compose the base MVS/ESA
operating environment. DFSMS/MVS consists of
DFSMSdfp, DFSMSdss, DFSMShsm, and DFSMSrmm.
with MVS/ESA SP compose the base MVS/ESA
operating environment. DFSMS/MVS consists of
DFSMSdfp, DFSMSdss, DFSMShsm, and DFSMSrmm.
direct access. (1) The capability to obtain data from
a storage device, or to enter data into a storage
device, in a sequence independent from their relative
position, by means of addresses indicating the
physical position of the data. (2) Contrast with serial
access.
a storage device, or to enter data into a storage
device, in a sequence independent from their relative
position, by means of addresses indicating the
physical position of the data. (2) Contrast with serial
access.
direct access storage device (DASD). A device in
which access time is effectively independent of the
location of the data. Usually disk storage.
which access time is effectively independent of the
location of the data. Usually disk storage.
directory. (1) A type of file containing the names and
controlling information for other files or other
controlling information for other files or other
directories. (2) An index that is used by a control
program to locate one or more blocks of data that are
stored in separate areas of a data set in direct access
storage.
program to locate one or more blocks of data that are
stored in separate areas of a data set in direct access
storage.
disk file. A set of related records on disk that are
treated as a unit.
treated as a unit.
distributed data. In SAA usage, data that is split
across two or more linked systems but which can be
accessed and processed as if it resided on one.
across two or more linked systems but which can be
accessed and processed as if it resided on one.
Distributed Data Management (DDM). A feature of
the System Support Program Product that allows an
application program to work on files that reside in a
remote system.
the System Support Program Product that allows an
application program to work on files that reside in a
remote system.
DL/I. See Data Language One.
DLIB. Distribution library. IBM-supplied partitioned
data sets on tape containing one or more components
that the user restores to disk for subsequent inclusion
in a new system.
data sets on tape containing one or more components
that the user restores to disk for subsequent inclusion
in a new system.
double-byte character set (DBCS). A set of
characters in which each character is represented by
2 bytes. Languages such as Japanese, Chinese, and
Korean, which contain more symbols than can be
represented by 256 code points, require double-byte
character sets. Because each character requires 2
bytes, the typing, display, and printing of DBCS
characters requires hardware and programs that
support DBCS. Contrast with single-byte character
set.
characters in which each character is represented by
2 bytes. Languages such as Japanese, Chinese, and
Korean, which contain more symbols than can be
represented by 256 code points, require double-byte
character sets. Because each character requires 2
bytes, the typing, display, and printing of DBCS
characters requires hardware and programs that
support DBCS. Contrast with single-byte character
set.
DSCB. See data set control block.
dsname. data set name. The name of a data set (1 -
40 characters) on the DD statement in the JCL or the
dsname operand of the TSO ALLOC command.
40 characters) on the DD statement in the JCL or the
dsname operand of the TSO ALLOC command.
dynamic address translation (DAT). In System/390
virtual storage systems, the change of a virtual
storage address to a real storage address during
execution of an instruction.
virtual storage systems, the change of a virtual
storage address to a real storage address during
execution of an instruction.
dynamic storage. A device that stores data in a
manner that permits the data to move or vary with
time such that the specified data are not always
available for recovery. Magnetic drum and disk
storage are dynamic nonvolatile storage. An acoustic
delay line is a dynamic volatile storage.
manner that permits the data to move or vary with
time such that the specified data are not always
available for recovery. Magnetic drum and disk
storage are dynamic nonvolatile storage. An acoustic
delay line is a dynamic volatile storage.
E
emulation. (1) The use of a data processing system
to imitate another data processing system, so that the
imitating system accepts the same data, executes the
same programs, and achieves the same results as the
imitated system. Emulation is usually achieved by
means of hardware or firmware. (2) The use of
programming techniques and special machine
to imitate another data processing system, so that the
imitating system accepts the same data, executes the
same programs, and achieves the same results as the
imitated system. Emulation is usually achieved by
means of hardware or firmware. (2) The use of
programming techniques and special machine
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