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CICS – Mainframe (LC)

CICS – Mainframe (LC). Course Schedule. Day1 - Introduction to CICS Day2 - Basic Mapping Support Day3 - Application Programming Day4 – File handling and Temporary Storage Day5 - Control Operations Day6 – Project Day7 - Project. Pre-requisites. MVS and TSO/ISPF subsystem VSAM concepts

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CICS – Mainframe (LC)

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  1. CICS – Mainframe (LC)

  2. Course Schedule • Day1 - Introduction to CICS • Day2 - Basic Mapping Support • Day3 - Application Programming • Day4 – File handling and Temporary Storage • Day5 - Control Operations • Day6 – Project • Day7 - Project

  3. Pre-requisites • MVS and TSO/ISPF subsystem • VSAM concepts • OLTP concepts • Programming in COBOL

  4. EvaluationMechanism

  5. References

  6. References • CICS Programming Using Cobol - http://kshop.ad.infosys.com/asp/Search/DispDoc.asp?DocNo=62157&KCURating=5.4&ContentType=BOK • Pseudo Conversational programming in CICS - • http://kshop.ad.infosys.com/asp/Search/DispDoc.asp?DocNo=58693&KCURating=5.4&ContentType=InternalTutorial • CICS Overview and useful - http://kshop.ad.infosys.com/asp/Search/DispDoc.asp?DocNo=11074&KCURating=8.27&ContentType=BOK • CICS - A Beginners guide - http://kshop.ad.infosys.com/asp/Search/DispDoc.asp?DocNo=7745&KCURating=7.78&ContentType=ExternalTutorial

  7. Introduction to CICS Day 1

  8. Objectives • What is CICS? • Brief History of CICS • Batch and Online Systems • CICS system components • Basic concepts of CICS • Concept of a transaction • CICS Control Tables • Concept of Multitasking, Multithreading and Quasi-reentrancy • Command level and Macro level programming • Conversational Vs Pseudo-conversational programming

  9. TERMINAL VTAM BTAM TCAM CICS VSAM DB2 DASD Application Programs What is CICS? (Customer Information Control System) IBM definition: “CICS is a DB/DC control system”.

  10. Brief History of CICS • Introduced by IBM in 1968 – ran only on IBM mainframes • CICS on many platforms • Introduction of Transaction Server

  11. Batch On-line • Jobs are submitted for execution by the processor at later time • Absence of any interaction from user • Program starts, processes all records and ends • Performance measure is throughput • When program ABENDS it just ends the program • Jobs submitted are executed immediately • User interaction is an usual thing • Program starts, process a record and ends • Performance measure is response time • When CICS program ABENDS it may bring down the entire system

  12. Features of CICS • A Data Base/Data Communication (DB/DC) control system • Is a generalized transaction processing interface • Provides on-line environment in batch OS • Is an operating system in itself • Runs as a batch job within the OS/390 OS • Many languages can be used for developing CICS programs – COBOL being the most common

  13. CICS Environment

  14. MVS OS Database Access method DL/1, DB2 Data Access method VSAM,BDAM Telecommunication Access Method VTAM, TCAM, BTAM Terminals DASD CICS Data handling Services Monitoring Services Data Communication Services System Services Application Program Services CICS Application Programs (COBOL, PL/1, Assembly) CICS Environment

  15. What does CICS do? • Telecommunication • Multitasking • Data access and transaction control • Inter System communication

  16. IBM 3270 Terminals • Mainly consists of 1. A CRT Monitor and 2. A Keyboard. • Examples: 1. 3278 (Monochrome, usually Green, White or Amber) 2. 3279 (7 different colours) • Has better Keyboard Layout • Keyboard could be configured for foreign languages

  17. CRT Monitor Capable of displaying up to 1920 characters along 24 rows and 80 columns. IBM 3270 Terminals

  18. Key board Aid Keys Non-Aid Keys PF keys PF1 to PF24 & ENTER PA keys PA1 to PA4 & CLEAR Alphabets, numbers punctuation and special characters. Allows transfer of data. Doesn’t allow transfer of data. IBM 3270 Terminals

  19. Some Basic Terminologies • Task: Task is a unit of work specific to a user • Transaction: A CICS program cannot be directly invoked and is done through a transaction • Difference between transaction and task is, although several users can invoke a transaction, each user initiates his own task

  20. Some Basic Terminologies Logical Unit of Work: A piece of work, that should be done completely or not done at all. Application: Is a collection of programs that accomplish some specific task for the end user

  21. CICS Nucleus – Control Programs • TCP(Terminal Control Program) • KCP(Task Control Program) • PCP(Program Control Program) • FCP (File Control Program) • SCP (Storage Control Program) and many more like TSP (Temporary Storage Program) and SIP (System Initialization Program)

  22. CICS Nucleus – Control Tables • TCT(Terminal Control Table) • PCT(Program Control Table) • PPT(Processing Program Table) • FCT (File Control Table) • RCT(Resource Control Table) • And many more…

  23. Inside CICS • Starting a transaction • Flow of control during a transaction Operating System Program Library File Control list screen Employee File Terminal Program EMPLIST BMS

  24. Transaction B021 PCT PPT Transaction Programs B011 PB011 B021 PB021 B031 PB013 Program Location PB011 In Storage PB021 On Disk PB031 In Storage Library Load Module PB011 PB011 PB031 PB031 PB021 PB021 PB011 CICS Address space PB021 Infosys Technologies Limited

  25. CICS Concepts • Macro level • Command level • Multitasking • Multithreading • Quasi reentrancy

  26. More CICS Concepts • Pseudo-conversationalprogramming • Conversational programming Operations Display list screen. Wait for user input. Receive list screen. Read employee records from the employee file. Display records in formatted form. Wait for the user input. Receive the screen. Depending on the function key populate new list. Redisplay the list. • TasksOperations • First 1. Display list screen. • Second 3. Receive list screen. • 4. Read employee records from the employee file. • 5. Display the records in formatted form. • Third 7. Receive the screen. • 8. Depending on the function key populate new list. • 9. Redisplay the list.

  27. Pseudo Conversation • Conversation • Sending a message to the terminal and receiving a response from the user is called as one conversation. • Ex.: Display a menu on the screen and receive an option from the user. • Modes of Conversation • Conversational Mode • Pseudo-Conversational Mode • Non-Conversational Mode

  28. Advantages of Pseudo -Conversation • Resources are best utilized (The Resources are released as soon as the program is suspended temporarily) • Looks as if it is in conversational mode • Better response time

  29. Native CICS Commands CESN: CICS Execute Sign ON CEDA: CICS Execute Definition and Administration CEMT: CICS Execute Master Terminal CECI: CICS Execute Command Interpreter CEDF: CICS Execute Debug Facility CMAC: CICS Messages for Abend Codes CESF: CICS Execute Sign OfF CEBR – CICS Execute temporary storage BRowse

  30. Summary • What is CICS? • Why CICS in MVS? • How is CICS similar to OS? • What are AID, PF, PA keys? • What are transactions and tasks? • What is Multitasking, Multithreading, Quasi-reentrancy? • What are the ways of starting a transaction? • What are the CICS tables? • What is conversational and pseudo-conversational programming? • What are the native CICS Commands

  31. Thank You!

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