MASARYK UNIVERSITY FACULTY OF INFORMATICS DIPLOMA THESIS System Information Gathering across Several Sysplexes under z/OS Vlastimil Jeřábek 2014 Statement I declare that this thesis is my original authorial work, which I developed on my own. All sources and literature that I have used in the development are properly quoted in the text and their fully qualified references to the relevant source are mentioned at the end of thesis. In addition I declare that all quoted literature and materials are publicly available which ensures preservation of all IBM policies about confidential material and customer information. Supervisor: doc. RNDr. Tomáš Pitner, Ph.D. I Thanks Primarily I would like to thank doc. RNDr. Tomáš Pitner, Ph.D. for academic guidance, reviews and mainly auspices over my thesis which mainframe theme not regularly taught and the faculty. Next thanks belongs to my colleagues, especially Tomáš Hláč and former colleague Paul Voyner, for all good technical advices and explanation of problems I encountered during programming. I would like to thank also to my employer for possibility of developing my program on test systems and improve my job related skills by working on diploma thesis. II Summary My diploma thesis introduces program developed mostly in REXX programming language under z/OS operation system running on mainframe computer. It consists of theoretical and practical part. Theoretical part is comprehensive due to fact there is only little common awareness about mainframe computers, z/OS environment and tools used for creation of final program. First it contains few words about IBM company as dominating distributor of mainframe computers and its management. Then follows part explaining what mainframe is, summarizing mainframe history, its capabilities, possibilities and finally whole concept of mainframe operating system called z/OS. Practical part contains little close up of programming languages used because they do not belong to commonly used languages. It is Restructured Extended Executor (REXX) and Job Control Language (JCL). Last section of practical part describes program itself. Motivation, usability and particular parts of code are depicted here along with problems encountered during development. End of thesis demonstrates program functionality and conclusion. III Keywords programming, programming language, Restructured Extended Executor (REXX), Job Control Language (JCL), Time Sharing Option (TSO), Interactive System Productivity Facility (ISPF), International Business Machines (IBM), Central Processing Complex (CPC), mainframe computer, IBM System z (zSeries), z/OS operating system, sysplex, data gathering, system settings, remote job executing IV Contents Contents 1 Introduction..................................................................................................................................... 2 2 About IBM Corporation................................................................................................................. 3 2.1 Pre-mainframe history of IBM............................................................................................. 3 2.2 Era of mainframes.................................................................................................................. 6 2.3 Personal computers, IBM near disaster .............................................................................. 8 2.4 IBM resurrection, present..................................................................................................... 9 3 Mainframe computing.................................................................................................................. 10 3.1 Mainframe generations and history .................................................................................. 11 3.2 Hardware configuration...................................................................................................... 15 3.2.1 Processor Book concept............................................................................................. 17 3.2.2 Multiple Chip Module............................................................................................... 18 3.2.3 zEnterprise EC12 models .......................................................................................... 20 3.2.4 System robustness ...................................................................................................... 20 3.3 Mainframe peripherals........................................................................................................ 21 3.3.1 Direct Access Storage Device.................................................................................... 21 3.3.2 Other peripherals........................................................................................................ 23 3.4 Typical mainframe installation.......................................................................................... 27 3.5 Basic operating system principles...................................................................................... 29 3.5.1 Mainframe memory and addressing........................................................................ 30 3.5.2 Data storing................................................................................................................. 32 3.5.3 Important system components and started tasks................................................... 34 3.5.4 Common middleware applications.......................................................................... 36 3.6 Spooling................................................................................................................................. 37 3.7 Batch processing .................................................................................................................. 37 3.8 Mainframe vs. distributed computing .............................................................................. 38 4 Programming under z/OS............................................................................................................ 42 4.1 Restructured Extended Executor....................................................................................... 44 4.2 Job Control Language and job processing........................................................................ 45 5 System information gathering utility.......................................................................................... 48 5.1 Motivation ............................................................................................................................ 48 5.2 How it works ........................................................................................................................ 49 5.2.1 System information gathering part.......................................................................... 50 5.2.2 Main program............................................................................................................. 53 5.3 Problems encountered in the implementation ................................................................ 54 5.4 Utility portability and modifiability.................................................................................. 55 6 Conclusion ..................................................................................................................................... 56 List of references ..................................................................................................................................... 57 List of used abbreviations ...................................................................................................................... 59 Introduction 1 Introduction Main motivation of this diploma thesis is to provide an overview of mainframe computing, currently widely used but invisible to many people. As most of us become daily users of this computer platform by making credit card transactions or means of transport reservations, still most people don’t know what mainframe is and many even don’t know that such platform exists. With each day growing online business and cashless payments is mainframe applied increasingly. The diploma thesis consists from theoretical and practical part. First chapter in theoretical part summarizes history of IBM Corporation as main producer of mainframe hardware, software, platform support and services. It covers history of IBM from its predecessors to the present. Then the most comprehensive chapter follows. Its purpose is to bring closer look at mainframe computing as a whole. At first general view of mainframes, difference between supercomputer and mainframe, mainframe common areas of activity and basic features is given. Further history of mainframes is described including mainframe generations. Next part speaks about mainframe hardware, most used peripherals and typical installation. Description of operating principles and important system components follows. Last part of theoretical chapter forms comparison between mainframes to distributed computing Practical part of the thesis speaks about programming languages under mainframe operating system. It focuses closer on two languages – Restructured Extended Executor and Job Control Language. These two languages were used to implementation of utility used for system information gathering which is described in last chapter. The utility is introduced, its capabilities are described, principles are shown and eventually further usages are discussed. 2 About IBM Corporation 2 About IBM Corporation IBM is an American corporation