IBM Z9 Planning Manual page 261

H
hardware system area (HSA). A logical area of
central storage, not addressable by application
programs, used to store Licensed Internal Code and
control information.
hex. Hexadecimal.
hexadecimal. (1) Pertaining to a selection, choice, or
condition that has 16 possible values or states. (I) (2)
Pertaining to a fixed-radix numeration system, with radix
of 16. (I) (3) Pertaining to a numbering system with
base of 16; valid numbers use the digits 0–9 and
characters A–F, where A represents 10 and F
represents 15.
HSA. Hardware system area.
I
I/O. Input/output.
ICF. Internal coupling facility.
ICP. Internal coupling facility peer channel.
ID. Identifier.
identifier (ID). (1) One or more characters used to
identify or name a data element and possibly to indicate
certain properties of that data element. (T) (2) A
sequence of bits or characters that identifies a program,
device, or system to another program, device, or
system. (3) In an ESCON Director, a user-defined
symbolic name of 24 characters or fewer that identifies
a particular ESCD.
IFL. Integrated Facility for Linux.
IFA. Integrated Facility for Applications. Also referred to
as zAAPs, or System z9 Application Assist Processors.
IML. Initial machine load.
IMS. Information Management System.
initial program load (IML). A procedure that prepares
a device for use.
initial program load (IPL). (1) The initialization
procedure that causes an operating system to
commence operation. (2) The process by which a
configuration image is loaded into storage at the
beginning of a work day or after a system malfunction.
(3) The process of loading system programs and
preparing a system to run jobs.
initialization. (1) The operations required for setting a
device to a starting state, before the use of a data
medium, or before implementation of a process. (T) (2)
Preparation of a system, device, or program for
operation. (3) To set counters, switches, addresses,
latches, or storage contents to zero or to other starting
values at the beginning of, or at the prescribed points
in, a computer program or process.
input/output (I/O). (1) Pertaining to a device whose
parts can perform an input process and an output
process at the same time. (I) (2) Pertaining to a
functional unit or channel involved in an input process,
output process, or both, concurrently or not, and to the
data involved in such a process. (3) Pertaining to input,
output, or both.
input/output configuration. The collection of channel
paths, control units, and I/O devices that attaches to the
processor.
input/output configuration data set (IOCDS). The
data set that contains an I/O configuration definition built
by the I/O configuration program (IOCP).
input/output configuration program (IOCP). A
program that defines to a system all the available I/O
devices and the channel paths.
interactive. Pertaining to a program or system that
alternately accepts input and then responds. An
interactive system is conversational; that is, a
continuous dialog exists between the user and the
system. Contrast with batch.
interface. (1) A shared boundary between two
functional units, defined by functional characteristics,
signal characteristics, or other characteristics as
appropriate. The concept includes the specification of
the connection of two devices having different functions.
(T) (2) Hardware, software, or both, that links systems,
programs, or devices.
interrupt. (1) A suspension of a process, such as
execution of a computer program caused by an external
event, and performed in such a way that the process
can be resumed. (A) (2) To stop a process in such a
way that it can be resumed. (3) In data communication,
to take an action at a receiving station that causes the
sending station to end a transmission. (4) To temporarily
stop a process.
interruption. Synonym for interrupt.
IOCDS. I/O configuration data set.
IOCP. I/O configuration program.
IOP. Input/Output processor.
IPL. Initial program load.
IRD. Intelligent Resource Director.
ITR. Internal throughput rate.
D-5
Glossary