link-edit. To create a loadable computer program by
means of a linkage editor.
load module. An application or routine in a form
suitable for execution. The application or routine has
been compiled and link-edited; that is, address
constants have been resolved.
load module library. A partitioned data set used to
store and retrieve load modules. See also object
module library, source module library.
local area network (LAN). (1) A computer network
located on a user′s premises within a limited
geographical area. Communication within a local area
network is not subject to external regulations;
however, communication across the LAN boundary
may be subject to some form of regulation. See also
wide area network. See figure 88. ñNote: A LAN does
not use store and forward techniques. (2) A network
in which a set of devices are connected to one
another for communication and that can be connected
to a larger network. See also token ring.
lock. (1) A serialization mechanism by means of
which a resource is restricted for use by the holder of
the lock. See exclusive lock, shared lock. (2) The
means by which integrity of data is ensured by
preventing more than one user from accessing or
changing the same data or object at the same time.
log data set. A data set consisting of the messages
or message segments recorded on auxiliary storage
by the ACF/TCAM logging facility.
logical device. (1) A file for conducting input or
output with a physical device. (2) A file for mapping
user I/O between virtual and real devices.
logical record. (1) A set of related data or words
considered to be a record from a logical viewpoint. (2)
A record from the standpoint of its content, function,
and use rather than its physical attributes, that is, a
record defined in terms of the information it contains.
(3) In CICS/VS, a data record sent by one transaction
program to another. The length of the record is
contained in a two-byte field immediately preceding
the record. (4) In VSAM, a unit of information
normally pertaining to a single subject; a logical
record is the user record requested of or given to the
data management function. (5) In COBOL, the most
inclusive data item.
M
main task. In VSE, the main program within a
partition in a multiprogramming environment.
maintenance. Any activity intended to retain a
functional unit in, or to restore it to, a state in which it
can perform its required function. Maintenance
includes keeping a functional unit in a specified state
by performing activities such as tests, measurements,
replacements, adjustments, and repairs.
MAS. Multi-Access Spool facility. A loosely
connected complex of JES2 members.
mass conversion. An automated process that
includes program translation, JCL conversion, and file
transfer. This process is what makes possible the
rapid switchover from VSE to MVS.
master console. In a system with multiple consoles,
the basic console used for communication between
the operator and the system.
MCS. (1) Multiple Console Support. A feature of MVS
that permits selective message routing to up to 32
operator′s consoles. (2) modification control
statement. An SMP/E control statement used to
package a SYSMOD. These statements describe the
elements of a program and the relationships that
program has with other programs that may be
installed on the same system.
menu. A list of options displayed to the user by a
data processing system, from which the user can
select an action to be initiated.
message data set. A data set on disk storage that
contains queues of messages awaiting transmission
to particular terminal operators or to the host system.
migrate. To move to a changed operating
environment, usually to a new release or version of a
system.
migration (VSE/MVS). The entire process of
transition from a VSE environment to an MVS
environment. Migration includes training, project
planning and management, system and configuration
setup, conversion design, and the conversion itself.
minidisk. Synonym for virtual disk
module. A program unit that is discrete and
identifiable with respect to compiling, combining with
other units, and loading; for example, the input to or
output from an assembler, compiler, linkage editor, or
executive routine.
multiprocessor. (1) A computer including two or
more processors that have common access to a main
storage. (2) A system of two or more processing units,
ALUs, or processors that can communicate without
manual intervention.
multitasking. A mode of operation that provides for
concurrent performance, or interleaved execution of
two or more tasks.
multithreading. Pertaining to concurrent operation of
more than one path of execution within a computer.
Glossary 575