CICS – Mainframe (LC)

2 Copyright © 2005, Infosys Technologies Ltd ER/CORP/CRS/TP01/003 Version No: 1.0 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 Copyright © 2005, Infosys Technologies Ltd ER/CORP/CRS/TP01/003 Version No: 1.0 Pre-requisites  MVS and TSO/ISPF subsystem  VSAM concepts  OLTP concepts  Programming in COBOL

4 Copyright © 2005, Infosys Technologies Ltd ER/CORP/CRS/TP01/003 Version No: 1.0 Evaluation Mechanism ComponentMarks Schedule Project50Day 6 & Day 7 Module Test50Day 8

5 Copyright © 2005, Infosys Technologies Ltd ER/CORP/CRS/TP01/003 Version No: 1.0 References TITLEAUTHORPUBLISHER CICS for COBOL programmer Doug LoweMike Murach & Associates CICS HandbookKageyamaTata McGraw Hill CICS command level Programming Alida M JatichJohn Wiley and Sons Inc., CICS using COBOLAndrew M. SuhyGalgotia

6 Copyright © 2005, Infosys Technologies Ltd ER/CORP/CRS/TP01/003 Version No: 1.0 References CICS Programming Using Cobol &KCURating=5.4&ContentType=BOK &KCURating=5.4&ContentType=BOK Pseudo Conversational programming in CICS - Rating=5.4&ContentType=InternalTutorial Rating=5.4&ContentType=InternalTutorial CICS Overview and useful - Rating=8.27&ContentType=BOK Rating=8.27&ContentType=BOK CICS - A Beginners guide - Rating=7.78&ContentType=ExternalTutorial Rating=7.78&ContentType=ExternalTutorial

Introduction to CICS Day 1

8 Copyright © 2005, Infosys Technologies Ltd ER/CORP/CRS/TP01/003 Version No: 1.0 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 Copyright © 2005, Infosys Technologies Ltd ER/CORP/CRS/TP01/003 Version No: 1.0 What is CICS? (Customer Information Control System) CICS VTAM BTAM TCAM Application Programs VSAM DB2 DASD TERMINAL IBM definition: “CICS is a DB/DC control system”.

10 Copyright © 2005, Infosys Technologies Ltd ER/CORP/CRS/TP01/003 Version No: 1.0 Brief History of CICS Introduced by IBM in 1968 – ran only on IBM mainframes CICS on many platforms Introduction of Transaction Server

11 Copyright © 2005, Infosys Technologies Ltd ER/CORP/CRS/TP01/003 Version No: 1.0 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 Copyright © 2005, Infosys Technologies Ltd ER/CORP/CRS/TP01/003 Version No: 1.0 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 Copyright © 2005, Infosys Technologies Ltd ER/CORP/CRS/TP01/003 Version No: 1.0 CICS Environment

14 Copyright © 2005, Infosys Technologies Ltd ER/CORP/CRS/TP01/003 Version No: 1.0 CICS Environment Database Access method DL/1, DB2 Telecommunication Access Method VTAM, TCAM, BTAM Data Access method VSAM,BDAM MVS OS Data handling Services Data Communication Services Monitoring Services System Services Application Program Services CICS CICS Application Programs (COBOL, PL/1, Assembly) Terminals DASD

15 Copyright © 2005, Infosys Technologies Ltd ER/CORP/CRS/TP01/003 Version No: 1.0 What does CICS do? Telecommunication Multitasking Data access and transaction control Inter System communication

16 Copyright © 2005, Infosys Technologies Ltd ER/CORP/CRS/TP01/003 Version No: 1.0 IBM 3270 Terminals Mainly consists of 1. A CRT Monitor and 2. A Keyboard. Examples: (Monochrome, usually Green, White or Amber) (7 different colours) Has better Keyboard Layout Keyboard could be configured for foreign languages

17 Copyright © 2005, Infosys Technologies Ltd ER/CORP/CRS/TP01/003 Version No: 1.0 IBM 3270 Terminals CRT Monitor Capable of displaying up to 1920 characters along 24 rows and 80 columns.

18 Copyright © 2005, Infosys Technologies Ltd ER/CORP/CRS/TP01/003 Version No: 1.0 IBM 3270 Terminals Key board Aid Keys PF keys PF1 to PF24 & ENTER PA keys PA1 to PA4 & CLEAR Non-Aid Keys Alphabets, numbers punctuation and special characters. Allows transfer of data. Doesn’t allow transfer of data.

19 Copyright © 2005, Infosys Technologies Ltd ER/CORP/CRS/TP01/003 Version No: 1.0 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 Copyright © 2005, Infosys Technologies Ltd ER/CORP/CRS/TP01/003 Version No: 1.0 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 Copyright © 2005, Infosys Technologies Ltd ER/CORP/CRS/TP01/003 Version No: 1.0 CICS Nucleus – Control Programs 1.TCP (Terminal Control Program) 2.KCP (Task Control Program) 3.PCP (Program Control Program) 4.FCP (File Control Program) 5.SCP (Storage Control Program) and many more like TSP (Temporary Storage Program) and SIP (System Initialization Program)

22 Copyright © 2005, Infosys Technologies Ltd ER/CORP/CRS/TP01/003 Version No: 1.0 CICS Nucleus – Control Tables 1.TCT (Terminal Control Table) 2.PCT (Program Control Table) 3.PPT (Processing Program Table) 4.FCT (File Control Table) 5.RCT(Resource Control Table) 6.And many more…

23 Copyright © 2005, Infosys Technologies Ltd ER/CORP/CRS/TP01/003 Version No: 1.0 Inside CICS Starting a transaction Flow of control during a transaction list screen File Control Program Library Employee File Operating System Terminal BMS Program EMPLIST

24 Copyright © 2005, Infosys Technologies Ltd ER/CORP/CRS/TP01/003 Version No: 1.0 Transaction B021 Transaction Programs B011 PB011 B021 PB021 B031 PB013 PCT Program Location PB011 In Storage PB021 On Disk PB031 In Storage PPT Library Load Module PB011 PB011 PB031 PB031 PB021 PB021 PB011 PB021 CICS Address space Infosys Technologies Limited

25 Copyright © 2005, Infosys Technologies Ltd ER/CORP/CRS/TP01/003 Version No: 1.0 CICS Concepts Macro level Command level Multitasking Multithreading Quasi reentrancy

26 Copyright © 2005, Infosys Technologies Ltd ER/CORP/CRS/TP01/003 Version No: 1.0 More CICS Concepts Conversational programming Pseudo-conversational programming Operations 1.Display list screen. 2.Wait for user input. 3.Receive list screen. 4.Read employee records from the employee file. 5.Display records in formatted form. 6.Wait for the user input. 7.Receive the screen. 8.Depending on the function key populate new list. 9.Redisplay the list. Tasks Operations 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 Copyright © 2005, Infosys Technologies Ltd ER/CORP/CRS/TP01/003 Version No: 1.0 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 Copyright © 2005, Infosys Technologies Ltd ER/CORP/CRS/TP01/003 Version No: 1.0 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 Copyright © 2005, Infosys Technologies Ltd ER/CORP/CRS/TP01/003 Version No: 1.0 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 Copyright © 2005, Infosys Technologies Ltd ER/CORP/CRS/TP01/003 Version No: 1.0 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 Copyright © 2005, Infosys Technologies Ltd ER/CORP/CRS/TP01/003 Version No: 1.0 Thank You!