IBM Z9 Planning Manual page 262

L
LIC. Licensed Internal Code.
Licensed Internal Code (LIC). Software provided for
use on specific IBM machines and licensed to
customers under the terms of IBM's Customer
Agreement. Microcode can be Licensed Internal Code
and licensed as such.
link. (1) In an ESCON or FICON environment, the
physical connection and transmission medium used
between an optical transmitter and an optical receiver. A
link consists of two conductors, one used for sending
and the other for receiving, providing a duplex
communication path. (2) In an ESCON or FICON I/O
interface, the physical connection and transmission
medium used between a channel and a control unit, a
channel and an ESCD, a control unit and an ESCD, or,
at times, between two ESCDs.
local. Synonym for channel-attached.
log. (1) To record, for example, to log all messages on
the system printer. (2) A record of events that have
occurred.
logical address. The address found in the instruction
address portion of the program status word (PSW). If
translation is off, the logical address is the real address.
If translation is on, the logical address is the virtual
address.
logical partition (LP). A subset of the processor
hardware that is defined to support the operation of a
system control program (SCP). See also logically
partitioned (LPAR) mode.
logical processor. In LPAR mode, a central processor
in a logical partition.
logically partitioned (LPAR) mode. A central
processor mode, available on the Configuration frame
when using the PR/SM feature, that allows an operator
to allocate processor unit hardware resources among
logical partitions. Contrast with basic mode.
logout. Log data that has been collected, formatted,
and recorded.
LP. Logical partition.
LPAR. Logically partitioned.
M
machine check. An error condition that is caused by
an equipment malfunction.
MB. Megabyte.
D-6
PR/SM Planning Guide
megabyte (MB). (1) A unit of measure for storage
size. One megabyte equals 1 048 576 bytes. (2)
Loosely, one million bytes.
monitor. A device that observes and records selected
activities within a data processing system for analysis.
multidrop. A network configuration in which there are
one or more intermediate nodes on the path between a
central node and an endpoint node. (T)
multidrop topology. A network topology that allows
multiple control units to share a common channel path,
reducing the number of paths between channels and
control units. Contrast with switched point-to-point
topology. See also point-to-point topology.
multiple image facility (MIF). A facility that allows
channels to be shared among PR/SM logical partitions
in an ESCON environment.
MVS/ESA. Multiple Virtual Storage/Enterprise Systems
Architecture.
N
network. (1) An arrangement of nodes and connecting
branches. (T) (2) A configuration of data processing
devices and software connected for information
exchange.
nybble. Equal to 4 bits.
O
offline. (1) Pertaining to the operation of a functional
unit that takes place either independently of, or in
parallel with, the main operation of a computer. (T) (2)
Neither controlled by, nor communicating with, a
computer. Contrast with online.
online. (1) Pertaining to the operation of a functional
unit when under the direct control of a computer. (T) (2)
Pertaining to a user&csq.s ability to interact with a
computer. (A) (3) Pertaining to a user's access to a
computer via a terminal. (A) (4) Controlled by, or
communicating with, a computer. Contrast with offline.
operating system. Software that controls the
execution of programs and that may provide services
such as resource allocation, scheduling, input/output
control, and data management. Although operating
systems are predominantly software, partial hardware
implementations are possible. (T)
operator console. (1) A functional unit containing
devices that are used for communications between a
computer operator and a computer. (T) (2) A display
used for communication between the operator and the
system, used primarily to specify information concerning
application programs and I/O operations and to monitor
system operation.