xvi IBM VM/370 Service Routines Program Logic
This publication explains the program logic
for each of the VM/370 service routines.
Because the service routines are unrelated,
they are discussed separately. One chapter
of this publication is dedicated to each
service routine (or logical group of
service routines).
Each chapter is structured similarly.
The following sections, where they are
applicable, are included in each chapter: Introducticn Method of Operation Program Organization Directory Data Areas Diagnostic Aids
The first section, the "Introduction,"
gives a brief description of the service
routine. This secticn explains what
functions the service routine performs and
tells how the program can be executed.
The second section, "Method of Operation," describes the program logic for
the service routine. Diagrams describe the
functions that the service routine performs
and the "Notes" section of each diagram
relates the function performed to the
coding in the program. The labels of the
related program sections are identified so
that you can easily find the area in the
program listing.
The "Program Organization" section
contains a variety of information, such as
entry points, data areas, and register
usage. If the service routine is complex,
there is a synopsis of the program modules
or program routines.
The "Directory" lists all the program
labels that are mentioned in the method of
operation diagrams with a cross reference
list indicating the diagram on which they
appear. Also, there is a brief description
of the function performed at the point in
the program corresponding to each label.
If the service routine contains more than
one module, the correct mcdule is
indicated. The "Directory" is intended to
help you quickly locate the section of the
chapter that describes a particular
function.
The "Data Areas" section contains
detailed descriptions of the control blocks
and data areas used by the service routine. Introduction The last section. "Diagnostic Aids,"
contains a cross-reference list of the
messages issued by the service routine.
The message number and text are included
with a label in the Frogram reasonably
close to the point where the .essage is
issued. Messages are usually helpful when
debugging a program problem. Illustrations There are two types of illustrations in
this publication: Figures Diagrams FIGURES All general illustraticns, such as data
areas and relationship drawings, are called
"Figures". Figures may aFpear in any
section of this publication. DIAGRAMS The method of operation drawings are called
"tiagrams". Diagrams consist of a drawing
and, very often, complementary notes. The
drawing has three distinct parts: Process Input Output The process block describes the action
taken by the service rcutine. The inFut
block shows the necessary input, such as
data areas and control statements. The
output block shows the resulting output,
such as initialized disks or copied files.
The process block is found in the center of
the drawing with the input block on the
left and the output blcck cn the right.
The Notes section aFpears below the
drawing; it consists of a detailed comment,
the module name (if the service routine
consists of more than one module), the
related program label, and a reference to
any additional information (where
appropriate) Introducticn 1
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