CICS – Mainframe (LC)
Course Schedule
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Day1 - Introduction to CICS
Day2 - Basic Mapping Support
Day3 - Application Programming
Day4 – File handling and Temporary Storage
Day5 - Control Operations
Day6 – Project
Day7 - Project
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Pre-requisites
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MVS and TSO/ISPF subsystem
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VSAM concepts
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OLTP concepts
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Programming in COBOL
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Evaluation Mechanism
Component
Marks
Schedule
Project
Module Test
50
50
Day 6 & Day 7
Day 8
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References
TITLE
AUTHOR
PUBLISHER
CICS for COBOL
programmer
Doug Lowe
Mike Murach & Associates
CICS Handbook
Kageyama
Tata McGraw Hill
CICS command level
Programming
Alida M Jatich
John Wiley and Sons Inc.,
CICS using COBOL
Andrew M. Suhy
Galgotia
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References
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CICS Programming Using Cobol -
http://kshop.ad.infosys.com/asp/Search/DispDoc.asp?DocNo=
62157&KCURating=5.4&ContentType=BOK
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Pseudo Conversational programming in CICS http://kshop.ad.infosys.com/asp/Search/DispDoc.asp?DocNo=58693&KCU
Rating=5.4&ContentType=InternalTutorial
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CICS Overview and useful http://kshop.ad.infosys.com/asp/Search/DispDoc.asp?DocNo=11074&KCU
Rating=8.27&ContentType=BOK
•
CICS - A Beginners guide http://kshop.ad.infosys.com/asp/Search/DispDoc.asp?DocNo=7745&KCU
Rating=7.78&ContentType=ExternalTutorial
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Introduction to CICS
Day 1
Objectives
• What is CICS?
– Brief History of CICS
– Batch and Online Systems
– CICS system components
• Basic concepts of CICS
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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
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What is CICS? (Customer
Information Control System)
IBM definition: “CICS is a DB/DC control system”.
TERMINAL
VTAM
BTAM
VSAM
CICS
DB2
TCAM
Application
Programs
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DASD
Brief History of CICS
• Introduced by IBM in 1968 – ran only on IBM
mainframes
• CICS on many platforms
• Introduction of Transaction Server
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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
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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
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CICS Environment
F ile S ystem
T erm inals
O P E R A T IN G S Y S T E M
B atch Job1
C IC S R E G IO N
PG M 1
PG M 2
PG M 3
B atch Job2
B atch Job3
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CICS Environment
MVS OS
Database
Access
method
DL/1, DB2
Data
Access
method
VSAM,BDAM
Telecommunication
Access Method
VTAM, TCAM, BTAM
DASD
Terminals
CICS
Monitoring Services
Data handling
Services
System Services
Application Program
Services
Data
Communication
Services
CICS Application Programs (COBOL, PL/1, Assembly)
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What does CICS do?
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Telecommunication
Multitasking
Data access and transaction control
Inter System communication
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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
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IBM 3270 Terminals
CRT Monitor
Capable of displaying up to 1920 characters
along 24 rows and 80 columns.
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IBM 3270 Terminals
Key board
Aid Keys
Non-Aid Keys
PF keys
PA keys
PF1 to PF24
&
PA1 to PA4
&
ENTER
CLEAR
Alphabets, numbers
punctuation and
special characters.
Allows transfer of data.
Doesn’t allow transfer of data.
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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
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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
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CICS Nucleus – Control Programs
1.
2.
3.
4.
5.
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)
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CICS Nucleus – Control Tables
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TCT (Terminal Control Table)
PCT (Program Control Table)
PPT (Processing Program Table)
FCT (File Control Table)
RCT(Resource Control Table)
And many more…
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Inside CICS
• Starting a transaction
• Flow of control during a transaction
Operating System
Program
File
list screen
Library
Control
Terminal
Program
EMPLIST
Employee
File
BMS
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Transaction
B021
PCT
Transaction
B011
B021
B031
PPT
Programs
PB011
PB021
PB013
CICS Address
space
Program
PB011
PB021
PB031
Location
In Storage
On Disk
In Storage
PB011
PB021
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Library Load Module
PB011
PB031
PB021
PB011
PB031
PB021
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CICS Concepts
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Macro level
Command level
Multitasking
Multithreading
Quasi reentrancy
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More CICS Concepts
• Pseudo-conversational
programming
• Conversational
programming
Operations
Tasks
1. Display list screen.
2. Wait for user input.
Operations
First
1. Display list screen.
Second
3. Receive list
screen.
3. Receive list screen.
4. Read employee records from the
employee file.
4. Read employee records
from the employee file.
5. Display records in formatted form.
5. Display the records in
formatted form.
6. Wait for the user input.
Third
7. Receive the screen.
8. Depending on the function key
populate new list.
7. Receive the screen.
8. Depending on the
function key populate new list.
9. Redisplay the list.
9. Redisplay the list.
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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
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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
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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
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Summary
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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, Quasireentrancy?
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
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Thank You!
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Introduction to CICS