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Towards More Usable Systems:

The LSRAD Report

Large
Systems
Requirements for
Application
Development

December 1979

.. . SHARE Inc .
Chicago, Illinois 60601
Copyright SHARE Inc., 1979. All Rights Reserved.

Published by SHARE Inc., a non-profit Delaware membership corporation. Permission to
reprint in whole or in part may be granted for educational and scientific purposes upon written
application to the Secretary,One lIlinois Center, 111 E. Wacker Dr., Chicago, lIlinois 6060l.
Permission is hereby granted to members of SHARE Inc. to reproduce this publication in
whole or in part solely for internal distribution within the member's organization and provided
the copyright notice printed above is set forth in full text on the title page of each item
reproduced. Printed in the United States of America.
iii

Preface
This is a report of the SHARE Large Systems Requirements for Application Development
(LSRAD) task force. This report proposes an evolutionary plan for MVS and VM/370that
will lead to simpler, more efficient and more usable operating systems. The report is intended
to address two audiences: the users of IBM's large operating systems and the developers of
those systems.
The views expressed in this report represent those of the individuals participatirtg iii the
task force rather than those of the sponsoring corporations.

The participants were:

Dana M. Becker Bell Laboratories; Naperville, Ill.
Jay A. Jonekait Tymshare; Cupertino, Calif.
Julie A. Lovinger General Motors Research; Warren, Mich.
Bruce S. Marshall Perkin-Elmer Corp; Danbury, Conn.
Jay Michlin Exxon Corp; Florham Park, N.J.
William Pashwa Bell Laboratories; Piscataway, N.J.
Marc Sewell Boeing Computer Services; Seattle, Wash.
Carol A. ' Schneier IBM, DSD; Poughkeepsie, N.Y.
Richard W. Suko IBM, DSD; Poughkeepsie, N.Y.
Albert B. Wilson, Jr. Boeing Computer Services; Seattle, Wash.

Acknowledgements
The LSRAD task force would like to thank our respective employers for the constant support
they have given us in the form of resources and encouragemeJ1t. We further thank the
individuals, both within and outside SHARE Inc., who reviewed the various drafts of this
report. We would like to acknowledge the contribution of the technical editors, Ruth Ashman,
Jeanine Figur, and Ruth Oldfield, and also of the clerical assistants, Jane Lovelette and
Barbara Simpson. "
Two computer systems proved invaluable for producing this report. Draft copies were
edited on "the Tymshare VM system. The final report was produced on -the IBM Yorktown
Heights experimental printer using the Yorktown Formatting Language under VM/CMS.
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v

Contents

Executive Sunimary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 1

Part I: Conceptual Framework. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 6

Defining the Problem 7
Task Force History. . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . .. .. . . . . . . .. 8
History of Operating Systems . . . . . . . .. . . . . . . . . . . . . . . . . . .. .. . . . . . .. 11
The Problem Today. . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . .. .. . . . . . . . 14
Fragmentation . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . .. .. . . . . . . . 16

The LSRAD Approach 19
System Synergism . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 20
Synergistic Computer Systems . . . . ........... . ...... . . ... . . ...... . . 22

The Whole System 26
A New Direction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
Programmer Productivity Benefits. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

Part II: Technical Proposals. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 35

Data in Memory 36
Named Spaces . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . .. .. . . . . . . .. 40
Sharing in Virtual Memory. . . . . . . . . . . . . . . . . . . .. . . . . . . .. .. . . . . . . .. 43
Extended Addressing . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . .. .. . . . . . ... 47
Device Independent I/O . . . . . . . . . . . . . . . . . . . . . .. . . . . . . .. .. . . . . . . .. 51
Hierarchical Storage Manager. . . . . . . . . . . . . . . . . .. . . . . . . .. .. . . . . . . .. 55

Enhanced Programming Environment 59
Integrated Command System. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 61
Data Access Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64
Subsystem Protection Mechanism . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . 69
Execution and Testing Environment 71

"Related Technical Material 78
Evolution Versus Revolution. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 79
Compatibility and Migration Considerations . . . . . . . . . . . . . . . . . . . . . . . . . .. 82
On Options . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 85
On Limits. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 87

Bibliography. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 90

Appendix: Survey Results . . . . . . . . . . . . . . . . . . . ........ '........ '. . . . . . . . . . .. 94
EXECUTIVE SUMMARY

The Large Systems Requirements for Application Development (LSRAD) task force was
organized by the IBM users' group, SHARE, Inc., to:
1. Identify the problems that confront the users of large IBM computer systems
2. Propose evolutionary operating :;ystem enhancements to improve the usability of both
MVS and VM/370

The task force findings and recommendations are summarized in this Executive Summary .
The summary makes no attempt to iustify the findings or recommendations or to present
detailed technical proposals. The deta Is are covered in the body of the report.
The impetus behind the formation of the task force was the realization that the approach-
ing bottleneck in the path of expanding data processing usage is programmer productivity.
There is a critical shortage of qualified programmers to address the growing applications
backlog in most companies today. Therefore, the task force was directed to propose a way to
make these programmers more productive.

THE PROBLEM

MVS and VM/370 were developed as a collection of subsystems, access methods, and
numerous programming tools. Each of these facilities was designed to meet a specific set of
needs. This segmented approach has led to an increasing set of complex and inconsistent
interfaces which the programmers must understand to use the systems. Consequently, MVS
and VM/370 users are encountering an environment which can best be described as fragment-
ed.
Due to the early origins of the operating systems, programmers must understand a great
deal about the computer hardware and software in order to move their data from external
storage devices to internal storage, manipulate it, and then return it to the external devices for
permanent storage. It is the management of internal (virtual) storage and external (file)
storage in the current systems that shapes the programming environment. The early origins are
also reflected in the complex and inconsistent utility and command languages provided today.
2 Executive Overview

Major problems face the data processing industry:
1. Operating systems have become increasingly complex and difficult to use.
2. Programmers are encountering significant conversion problems for current applications
with each new hardware device or release of an operating system.
3. Software maintenance costs are taking an ever-increasing portion of the data processing
budget.
4. Programmer training .and retraining time and costs are continuing to rise.

APPROACH

The task force decided that the best place to introduce staged, evolutionary change which
benefits the most users is in the foundation of the operating systems. Historically. most
changes have been made as additions to the systems, such as in the languages or in the
subsystems. This has led to fragmentation. A benefit provided by a change to one subsystem
or language is not benificial to the rest of the system. The LSRAD task force is suggesting
change at the foundation of the operating systems, where the leverage is greatest. Whatever is
done in the operating 'lystems can benefit all subsystems and all languages while being
integrated into a consistf nt programming environment.
The task force recognizes the need for evolutionary change, rather than revolutionary
change, and the operatlllg system is the logical place for implementation. The operating
system can, and must, c