Front cover Introduction to the New Mainframe z/OS Basics Basic mainframe concepts, including usage and architecture z/OS fundamentals for students and beginners Mainframe hardware and peripheral devices Mike Ebbers John Kettner Wayne O’Brien Bill Ogden ibm.com/redbooks International Technical Support Organization Introduction to the New Mainframe: z/OS Basics March 2011 SG24-6366-02 Note: Before using this information and the product it supports, read the information in “Notices” on page xi. Third Edition (March 2011) © Copyright International Business Machines Corporation 2006, 2009, 2011. All rights reserved. Note to U.S. Government Users Restricted Rights -- Use, duplication or disclosure restricted by GSA ADP Schedule Contract with IBM Corp. Contents Notices . xi Trademarks . xii Preface . xiii How this text is organized . xiv How each chapter is organized . xiv The team who wrote this book . xv Acknowledgements . xvi Now you can become a published author, too! . xix Comments welcome. xix Stay connected to IBM Redbooks . xix Summary of changes . xxi March 2011, Third Edition . xxi August 2009, Second Edition . xxi Part 1. Introduction to z/OS and the mainframe environment Chapter 1. Introduction to the new mainframe . 3 1.1 The new mainframe. 4 1.2 The System/360: A turning point in mainframe history . 4 1.3 An evolving architecture . 5 1.4 Mainframes in our midst . 8 1.5 What is a mainframe . 9 1.6 Who uses mainframe computers. 12 1.7 Factors contributing to mainframe use . 15 1.8 Typical mainframe workloads . 22 1.9 Roles in the mainframe world . 29 1.10 z/OS and other mainframe operating systems . 37 1.11 Introducing the IBM zEnterprise System . 40 1.12 Summary . 41 1.13 Questions for review . 42 1.14 Topics for further discussion . 42 Chapter 2. Mainframe hardware systems and high availability . 45 2.1 Introduction to mainframe hardware systems . 46 2.2 Early system design . 47 2.3 Current design. 50 2.4 Processing units . 59 © Copyright IBM Corp. 2006, 2009, 2011. All rights reserved. iii 2.5 Multiprocessors . 62 2.6 Disk devices . 63 2.7 Clustering . 65 2.8 Basic shared DASD. 66 2.9 What is a sysplex . 69 2.10 Intelligent Resource Director . 75 2.11 Platform Performance Management with zEnterprise. 76 2.12 Typical mainframe system growth. 77 2.13 Continuous availability of mainframes. 78 2.14 Summary . 87 2.15 Questions for review . 88 2.16 Topics for further discussion . 89 2.17 Exercises. 89 Chapter 3. z/OS overview. 91 3.1 What is an operating system . 92 3.2 What is z/OS . 92 3.3 Overview of z/OS facilities. 99 3.4 Virtual storage and other mainframe concepts . 101 3.5 What is workload management . 126 3.6 I/O and data management. 129 3.7 Supervising the execution of work in the system . 131 3.8 Cross-memory services. 143 3.9 Defining characteristics of z/OS . 144 3.10 Understanding system and product messages . 146 3.11 Predictive failure analysis . 150 3.12 z/OS and other mainframe operating systems . 151 3.13 A brief comparison of z/OS and UNIX. 152 3.14 Additional software products for z/OS . 155 3.15 Middleware for z/OS . 156 3.16 The new face of z/OS . 157 3.17 Summary . 159 3.18 Questions for review . 161 3.19 Topics for further discussion . 163 Chapter 4. TSO/E, ISPF, and UNIX: Interactive facilities of z/OS . 165 4.1 How do we interact with z/OS . 166 4.2 Time Sharing Option/Extensions overview . 166 4.3 ISPF overview . 172 4.4 z/OS UNIX interactive interfaces. 188 4.5 Summary . 194 4.6 Questions for review . 195 4.7 Exercises. 196 iv Introduction to the New Mainframe: z/OS Basics Chapter 5. Working with data sets. 203 5.1 What is a data set . 204 5.2 Where are data sets stored . 205 5.3 What are access methods. 206 5.4 How are DASD volumes used. 206 5.5 Allocating a data set . 208 5.6 How data sets are named . 208 5.7 Allocating space on DASD volumes through JCL . 210 5.8 Data set record formats. 211 5.9 Types of data sets . 214 5.10 What is Virtual Storage Access Method . ..