IBM System/360

EXECUTE CHANNEL PROGRAM (EXCP) MACRO-INSIRUCTION
This chapter contains a general
description of the function and application
of the Execute Channel Program (EXCP)
macro-instruction, accompanied by descrip-
tions of specific control blocks and macro-
instructions used with EXCP. Factors that
affect the operation of EXCP, such as
device variations and program modification,
are also discussed.
The EXCP macro~instruction provides you
with a device-dependent means of performing
the I/O operations. Before reading this
chapter, you should be familiar with system
functions and with the structure of control
blocks, as well as with the operational
characteristics of the I/O devices required
by your channel programs. Operational
characteristics of specific I/O devices are
contained in IBM System Reference Library
publications for each device.
Documentation of the internal logic of
the input/output supervisor can be obtained
through your IBM Branch Office.
PREREQUISITE PUBLICATIONS
The IBM System/360 Operating System:
Data Management publication (Form C28-6537)
explains the standard procedures for I/O
processing under the operating system.
The IBM System/360 Operating System:
Assemtler Language publication (Form
C28-6514) contains the information neces-
sary to code programs in the assembler
language.
The IBM System/360 Operating System:
Control Program Services publication (Form
C28-6541) describes the system macro-
instructions that can be used in programs
coded in the assembler language.
The IBM System/360 Opezating System:
System Control Block publication (Forro
C28-6628) contains format and field de-
scriptions of the system control clocks
referred to in this chapter.
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