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Understanding CICS and IMS Transaction Managers on z/OS

This chapter provides a comprehensive overview of the role of CICS (Customer Information Control System) in online transaction processing on z/OS. It covers essential concepts such as CICS programs, transactions, conversational programming, and web-enabling technologies. The chapter also delves into IMS (Information Management System), its components, and its messaging systems. Learn how CICS and IMS work together to manage resources and ensure data integrity, allowing multiple users to execute applications efficiently. Key programming commands and services are discussed for practical application development.

jelani-freeman
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Understanding CICS and IMS Transaction Managers on z/OS

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  1. Chapter 11 Understanding transaction managers on z/OS

  2. Chapter 11 objectives • Be able to: • Explain the role of CICS in online transaction processing • Describe CICS programs, CICS transactions, and CICS tasks • Explain what conversational and pseudo-conversational programming is • Explain CICS and Web-enabling • Discuss the IMS components

  3. BMP BMS conversational DBMS CICS TS CICS command IRLM bind transaction CICS command view modified source task/thread region PSB IMS TM transaction unit of work task/thread SPUFI SQLJ SYSADM EXPLAIN Key terms in this chapter

  4. What is CICS? • Customer Information Control System • Transactional subsystem of z/OS which: • run online applications • the same time, many users, same application(s) • manages the sharing of resources • integrity of data • prioritization of execution, with fast response.

  5. CICS in a z/OS system

  6. Languages & Platforms • Languages: • COBOL • OO COBOL • C • C++ • JAVA • PL/I • Assembler • Platforms: • zSeries (z/OS, OS/390, VSE) • Intel servers • TXSeries (AIX, HP-UX, Solaris and Windows)

  7. CICS Programming roadmap • Design application • Write & test program (includes compiling) • Define program & transaction in CICS resources • Define other resources (files, queues, etc…) in CICS resources • Make resources known to CICS

  8. Conversational Pseudo-Conversational

  9. Conversational Pseudo-Conversational

  10. CICS Programming commands • General format: • EXECUTE CICS (or EXEC CICS) + command • e.g. in COBOL: • EXEC CICS function option option ... END-EXEC. • CICS command example : • EXEC CICS • READ FILE(‘ACCTFIL’) RIDFLD(ACCTC) UPDATE ... • END-EXEC.

  11. CICS transaction flow

  12. CICS transaction flow (Cont…)

  13. CICS transaction flow (Cont…)

  14. CICS services for Application Programs • Application program interface: use CICS commands • Terminal control services: use Basic Mapping Support (BMS) • File & database control services: • CICS file control (mainly VSAM) • Database control (DL/I & DB2) • Other CICS Services: Task Control - Program Control - Temporary Storage (TS) & Transient Data Control (TD) - Interval Control - Storage Control - Dump & Trace Control

  15. Defining the screens • BMS macros: a form of assembler language • Result of an assembles : Physical Map • Physical map contains info to : • build the screen • merge variable data between program & screen • send variables back to program

  16. Program Control

  17. Example of CICS application user screen

  18. CICS and Web-enabling • 4 major elements of web-enabled applications: • Presentation logic • Integration logic • Business logic • Data logic

  19. CICS Web support

  20. CICS Transaction Gateway

  21. What is IMS? • Information Management System • 3 components: • The Transaction Manager (TM) • the Database Manager (DB) • Set of system services, providing common services to the other 2

  22. IMS overview

  23. IMS Transaction Manager messages • Four types of messages: • Transactions • To go to another logical destination • Commands for IMS • For the IMS APPC feature to process

  24. Summary • The continued growth of the Internet has caused many corporations to consider the best ways to make their legacy systems available to users on the Internet. • CICS is a transactional processing subsystem. CICS applications are traditionally run by submitting a transaction request. • Information Management System (IMS) consists of three components: • Transaction Manager (TM) • Database Manager (DB) • A set of system services common to both TM and DB

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