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Introduction to the New Mainframe: z/OS Basics
Preface This IBM® Redbooks® publication provides students of information systems technology with the background knowledge and skills necessary to begin using the basic facilities of a mainframe computer. It is the first in a planned series of book designed to introduce students to mainframe concepts and help prepare them for a career in large systems computing. For optimal learning, students are assumed to have successfully completed an introductory course in computer system concepts, such as computer organization and architecture, operating systems, data management, or data communications. They should also have successfully completed courses in one or more programming languages, and be PC literate. This book can also be used as a prerequisite for courses in advanced topics or for internships and special studies. It is not intended to be a complete text covering all aspects of mainframe operation or a reference book that discusses every feature and option of the mainframe facilities. Others who will benefit from this book include experienced data processing professionals who have worked with non-mainframe platforms, or who are familiar with some aspects of the mainframe but want to become knowledgeable with other facilities and benefits of the mainframe environment. As we go through this course, we suggest that the instructor alternate between text, lecture, discussions, and hands-on exercises. Many of the exercises are cumulative, and are designed to show the student how to design and implement the topic presented. The instructor-led discussions and hands-on exercises are an integral part of the course material, and can include topics not covered in this textbook. In this course, we use simplified examples and focus mainly on basic system functions. Hands-on exercises are provided throughout the course to help students explore the mainframe style of computing. At the end of this course, you will know: Basic concepts of the mainframe, including its usage, and architecture Fundamentals of z/OS®, a widely used mainframe operating system Mainframe workloads and the major middleware applications in use on mainframes today The basis for subsequent course work in more advanced, specialized areas of z/OS, such as system administration or application programming
How this text is organized This text is organized in four parts, as follows: Part 1, “Introduction to z/OS and the mainframe environment” on page 1 provides an overview of the types of workloads commonly processed on the mainframe, such as batch jobs and online transactions. This part of the text helps students explore the user interfaces of z/OS, a widely used mainframe operating system. Discussion topics include TSO/E and ISPF, UNIX® interfaces, job control language, file structures, and job entry subsystems. Special attention is paid to the users of mainframes and to the evolving role of mainframes in today’s business world. Part 2, “Application programming on z/OS” on page 297 introduces the tools and utilities for developing a simple program to run on z/OS. This part of the text guides the student through the process of application design, choosing a programming language, and using a runtime environment. Part 3, “Online workloads for z/OS” on page 399 examines the major categories of interactive workloads processed by z/OS, such as transaction processing, database management, and web serving. This part includes discussions about several popular middleware products, including IBM DB2®, CICS®, and IBM WebSphere® Application Server. Part 4, “System programming on z/OS” on page 527 provides topics to help the student become familiar with the role of the z/OS system programmer. This part of the text includes discussions of system libraries, starting and stopping the system, security, network communications, and the clustering of multiple systems. We also provide an overview of mainframe hardware systems, including processors and I/O devices. In this text, we use simplified examples and focus mainly on basic system functions. Hands-on exercises are provided throughout the text to help students explore the mainframe style of computing. Exercises include entering work into the system, checking its status, and examining the output of submitted jobs.
How each chapter is organized Each chapter follows a common format: Objectives for the student Topics that teach a central theme related to mainframe computing Summary of the main ideas of the chapter A list of key terms introduced in the chapter
Introduction to the New Mainframe: z/OS Basics
Questions for review to help students verify their understanding of the material Topics for further discussion to encourage students to explore issues that extend beyond the chapter objectives Hands-on exercises to help students reinforce their understanding of the material
The team who wrote this book John Kettner revised the second edition of this text. He is a Consulting IT Architect in the Systems z and zEnterprise sales group. He has 37 years of mainframe experience and holds a Bachelor of Science degree in Computer Science from L.I.U. His specialties are working with customers with IBM System z® internals, technical newsletters, and customer lecturing. John has written several IBM Redbooks and contributes to various education programs throughout IBM. Special thanks to the following advisors: Rick Butler, Bank of Montreal Timothy Hahn, IBM Raleigh Pete Siddall, IBM Hursley The first edition of this text was produced by technical specialists working at the International Technical Support Organization, Poughkeepsie Center, who also reviewed and revised the third edition: Mike Ebbers has worked with mainframe systems at IBM for 32 years. For part of that time, he taught hands-on mainframe classes to new hires just out of college. Mike currently creates IBM Redbooks, a popular set of product documentation that can be found at: http://www.ibm.com/redbooks Wayne O’Brien is an Advisory Software Engineer at IBM Poughkeepsie. Since joining IBM in 1988, he has developed user assistance manuals and online help for a wide variety of software products. Wayne holds a Master of Science degree in Technical Communications from Rensselaer Polytechnic Institute (RPI) of Troy, New York.
In addition, the following technical specialist helped produce the first edition of this text while working at the International Technical Support Organization, Poughkeepsie Center: Bill Ogden is a retired IBM Senior Technical Staff Member. He holds a Bachelor of Science degree in Electrical Engineering and a Master of Science degree in Computer Science. He has worked with mainframes since 1962 and with z/OS since it was known as OS/360 Release 1/2. Since joining the ITSO in 1978, Bill has specialized in encouraging users new to the operating system and associated hardware.
Acknowledgements The following people are gratefully acknowledged for their contributions to this project: Dan Andrascik is a senior at the Pennsylvania State University, majoring in Information Science and Technology. Dan is proficient in computer languages (C++, Visual Basic, HTML, XML, and SQL), organizational theory, database theory and design, and project planning and management. During his internship with the ITSO organization at IBM Poughkeepsie, Dan worked extensively with elements of the IBM eServer™ zSeries® platform. Rama Ayyar is a Senior IT Specialist with the IBM Support Center in Sydney, Australia. He has 20 years of experience with the MVS™ operating system and has been in the IT field for over 30 years. His areas of expertise include TCP/IP, security, storage management, configuration management, and problem determination. Rama holds a Master’s degree in Computer Science from the Indian Institute of Technology, Kanpur. Emil T. Cipolla is an information systems consultant in the United States with 40 years of experience in information systems. He holds Master’s degrees in Mechanical Engineering and Business Administration from Cornell University. Emil is currently an adjunct instructor at the college level. Mark Daubman is a senior at St. Bonaventure University, majoring in Business Information Systems with a minor concentration in Computer Science. As part of his internship with IBM, Mark worked extensively with many of the z/OS interfaces described in this textbook. After graduation, Mark plans to pursue a career in mainframes.
Introduction to the New Mainframe: z/OS Basics
Myriam Duhamel is an IT Specialist in Belgium. She has 20 years of experience in application development and has worked at IBM for 12 years. Her areas of expertise include development in different areas of z/OS (such as COBOL, PL/I, CICS, DB2, and WebSphere MQ). Myriam currently teaches courses in DB2 and WebSphere MQ. Per Fremstad is an IBM-certified I/T Specialist from the IBM Systems and Technology group in IBM Norway. He has worked for IBM since 1982 and has extensive experience with mainframes and z/OS. His areas of expertise include the web, WebSphere for z/OS, and web enabling of the z/OS environment. He teaches frequently on z/OS, zSeries, and WebSphere for z/OS topics. Per holds a Bachelor of Science degree from the University of Oslo, Norway. Luis Martinez Fuentes is a Certified Consulting IT Specialist (Data Integration discipline) with the Systems and Technology Group, IBM Spain. He has 20 years of experience with IBM mainframes, mainly in the CICS and DB2 areas. He is currently working in technical sales support for new workloads on the mainframe. Luis is a member of the Iberia Technical Expert Council, which is affiliated with the IBM Academy of Technology. Luis teaches about mainframes at two universities in Madrid. Miriam Gelinski is a staff member of Maffei Consulting Group in Brazil, where she is responsible for supporting customer planning and installing mainframe software. She has five years of experience in mainframes. She holds a Bachelor's degree in Information Systems from Universidade São Marcos in Sao Paulo. Her areas of expertise include the z/OS operating system, its subsystems, and TSO and ISPF. Michael Grossmann is an IT Education specialist in Germany with nine years of experience as a z/OS system programmer and instructor. His areas of expertise include z/OS education for beginners, z/OS operations, automation, mainframe hardware, and Parallel Sysplex®. Olegario Hernandez is a former IBM Advisory Systems Engineer in Chile. He has more than 35 years of experience in application design and development projects for mainframe systems. He has written extensively on the CICS application interface, systems management, and grid computing. Olegario holds a degree in Chemical Engineering from Universidad de Chile. Roberto Yuiti Hiratzuka is an MVS system programmer in Brazil. He has 15 years of experience as a mainframe system programmer. Roberto holds a degree in Information Systems from Faculdade de Tecnologia Sao Paulo (FATEC-SP). John Kettner, whose contributions were noted earlier.
Georg Müller is a student at the University of Leipzig in Germany. He has three years of experience with z/OS and mainframe hardware. He plans to complete his study with a Master's degree in Computer Science next year. For this textbook, Georg wrote topics about WebSphere MQ and HTTP Server, coded sample programs, and helped to verify the final sequence of learning modules. Rod Neufeld is a Senior Technical Services Professional in Canada. He has 25 years of experience in MVS and z/OS system programming. His areas of expertise include z/OS systems software and support, Parallel Sysplex, and business continuance and recovery. Rod holds an Honors Bachelor of Science degree from the University of Manitoba. Paul Newton is a Senior Software Engineer in the Dallas, Texas, IBM Developer Relations Technical Support Center. He has 25 years of experience with IBM mainframe operating systems, subsystems, and data networks. Paul holds a degree in Business Administration from the University of Arizona. Bill Seubert is a zSeries Software Architect in the United States. He has over 20 years experience in mainframes and distributed computing. He holds a Bachelor’s degree in Computer Science from the University of Missouri, Columbia. His areas of expertise include z/OS, WebSphere integration software, and software architecture. Bill speaks frequently to IBM clients about integration architecture and enterprise modernization. Henrik Thorsen is a Senior Consulting IT Specialist at IBM Denmark. He has 25 years of mainframe experience and holds an Master of Science degree in Engineering from the Technical University in Copenhagen and a Bachelor of Science degree in Economics from Copenhagen Business School. His specialties are z/OS, Parallel Sysplex, high availability, performance, and capacity planning. Henrik has written several IBM Redbooks and other documents and contributes to various education programs throughout IBM and the zSeries technical community. Andy R. Wilkinson is an IT Specialist in the United Kingdom. He has 25 years of experience in reservation systems and z/OS system programming, and has worked at IBM for six years. His areas of expertise include hardware configuration and SMP/E. Andy holds a degree in Materials Science and Technology from the University of Sheffield and a degree in Computing from the Open University. Lastly, special thanks to the editors at the ITSO center in Poughkeepsie, New York: Terry Barthel Ella Buslovich and Linda Robinson (graphics) Alfred Schwab
Introduction to the New Mainframe: z/OS Basics
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Introduction to the New Mainframe: z/OS Basics
Summary of changes This section describes the technical changes made in this edition of the book and in previous editions. This edition might also include minor corrections and editorial changes that are not identified. Summary of Changes for SG24-6366-02 for Introduction to the New Mainframe: z/OS Basics as created or updated on January 4, 2012.
March 2011, Third Edition This revision reflects the addition, deletion, or modification of new and changed information described below.
New and changed information This edition adds information about the IBM System z Enterprise hardware.
August 2009, Second Edition This revision reflects the addition, deletion, or modification of new and changed information described below.
New and changed information Chapters 1 through 3 were updated with the latest System z hardware and software information. Chapter 8 received additional information about application development on the mainframe. Added Appendix F, which includes the Console Operator commands.
Introduction to z/OS and the mainframe environment Welcome to mainframe computing! We begin this text with an overview of the mainframe computer and its place in today’s information technology (IT) organization. We explore the reasons why public and private enterprises throughout the world rely on the mainframe as the foundation of large-scale computing. We discuss the types of workloads that are commonly associated with the mainframe, such as batch jobs and online or interactive transactions, and the unique manner in which this work is processed by a widely used mainframe operating system, that is, z/OS. Throughout this text, we pay special attention to the people who use mainframes and to the role of the new mainframe in today’s business world.