CICS

• CICS

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CICS

1 'Customer Information Control System (CICS)' is a transaction

processing system|transaction server that runs primarily on IBM mainframe

systems under z/OS and z/VSE.


CICS

1 CICS is middleware designed to support rapid, high-volume online

transaction processing. A CICS transaction is a unit of processing

initiated by a single request that may affect one or more objects. This processing is usually interactive

(screen-oriented), but background transactions are possible.


CICS

1 CICS provides services that extend or replace the functions of the

Operating System and are more efficient than the generalized

services in the Operating System and simpler for programmers to use,

particularly with respect to communication with diverse terminal

devices.


CICS

1 Applications developed for CICS may be written in a variety of programming

languages and use CICS-supplied language extensions to interact with resources such as files, database connections, terminals,

or to invoke functions such as web services. CICS manages the entire

transaction such that if for any reason a part of the transaction fails all recoverable

changes can be backed out.


CICS

1 While CICS has its highest profile among financial institutions such as banks and

insurance companies, over 90 percent of Fortune 500 companies are reported to run CICS along with many government entities.

CICS is also widely used by many smaller organizations. CICS is used in bank-teller

applications, automated teller machine|ATM systems, industrial production control

systems, insurance applications, and many other types of interactive applications.


CICS

1 Recent CICS Transaction Server enhancements include support for Web services and Enterprise Java

Beans (EJBs), Event processing, Atom (standard)|Atom feeds, and

Representational State Transfer|RESTful interfaces.


CICS

1 CICS Transaction Server version 4.2, which became General availability release|generally available on 24 June 2011, includes support for


CICS - History

1 CICS was preceded by an earlier, single threaded transaction

processing system, IBM MTCS. An 'MTCS-CICS bridge' was later

developed to allow these transactions to execute under CICS

with no change to the original application programs.


CICS - History

1 It became clear immediately that it had applicability to many other

industries, so the Public Utility prefix was dropped with the introduction of the first release of the CICS Program

Product on July 8, 1969, not long after IBM Information Management System|IMS database management

system


CICS - History

1 In 1974, CICS development responsibility was shifted to IBM's

Hursley, United Kingdom Laboratory, where development work continues

today.


CICS - Early evolution

1 CICS originally only supported a few IBM-brand devices like the 1965 IBM 2741 Selectric (golf ball) typewriter based terminal. The 1964 IBM 2260 and 1972 IBM 3270 video display terminals were widely used later.



1 In the early days of IBM mainframes, computer software was free - bundled at no extra charge with computer hardware.

The OS/360 Operating System and application support software like CICS

were open to IBM customers long before the open source software initiative.

Corporations like Standard Oil of Indiana (Amoco) made major contributions to

CICS.



1 When CICS was delivered to Amoco with Teletype Model 33 ASR support, it caused the entire OS/360 Operating System to crash (including non-CICS application programs). The majority of the CICS

Terminal Control Program (TCP - the heart of CICS) and part of OS/360 had to be

laboriously redesigned and rewritten by Amoco Production Company in Tulsa

Oklahoma. It was then given back to IBM for free distribution to others.



1 In a few years, CICS generated over $60 billion in new hardware revenue

for IBM, and became their most-successful mainframe software

product.



1 In 1980, IBM executives failed to heed Ben Riggins' strong suggestions

that IBM should provide their own EBCDIC-based Operating System and

integrated-circuit microprocessor chip for use in the IBM Personal Computer as a CICS Thin client|

intelligent terminal (instead of the incompatible Intel chip, and

immature ASCII-based Microsoft 1980 DOS)



1 Because of the limited capacity of even large processors of that era every CICS installation was required to assemble the source code for

all of the CICS system modules after completing a process similar to system generation

(sysgen), called CICSGEN, to establish values for conditional assembly language statements. This process allowed each customer to exclude support from CICS itself for any feature they did

not intend to use, such as device support for terminal types not in use.



1 CICS owes its early popularity to its relatively efficient implementation

when hardware was very expensive, its multi-threaded processing

architecture, its relative simplicity for developing terminal-based real-time transaction applications, and many

open-source customer contributions, including both debugging and feature

enhancement.https://store.theartofservice.com/itil-2011-foundation-complete-certification-kit-fourth-edition-study-guide-ebook-and-online-course.html

CICS - Z notation

1 Part of CICS was formalized using the Z notation in the 1980s and 1990s in

collaboration with the Oxford University Computing Laboratory, under the leadership of Sir Tony Hoare. This work won a Queen's

Awards for Enterprise|Queen's Award for Technological Achievement.


CICS - CICS and the World Wide Web

1 CICS Transaction Server (TS) 2.1 introduced the capability for CICS transactions to be invoked via an HTTP request. This allowed CICS

transactions to participate as servers in a Plain Old XML|POX or

Representational State Transfer|REST conversation.



1 CICS Transaction Server 2.3 added new EJB tracing capabilities, and new JCICS classes, allowing the invocation of CICS services using Java. End-to-end debugging was also introduced,

making it easier to debug applications, from the Java client to

the CICS application.



1 CICS supports a number of industry standard and specifications including SOAP Version 1.1 and Version 1.2, Web services

distributed transactions (WS-Atomic Transaction) and XML Encryption and

Signing.IBM, 2010, CICS TS 4.1 Information Centre,

http://publib.boulder.ibm.com/infocenter/cicsts/v4r1/index.jsp?topic=/

com.ibm.cics.ts.webservices.doc/concepts/dfhws_standards.html



1 The CICS Web Services Assistant includes two batch processing

utilities, DFHWS2LS and DFHLS2WS, which are used to map Web Services

Description Language|WSDL to programming language structures

and vice versa, respectively.



1 In this case, the application developer populates the language structure

corresponding to the method they wish to invoke, writes the structure to the DFHWS-

BODY CICS container, and executes the INVOKE WEBSERVICE Application

Programming Interface (API). Execution of the API is synchronous, on return the

DFHWS-BODY contains the response from the invoked web service mapped to a

language structure.https://store.theartofservice.com/itil-2011-foundation-complete-certification-kit-fourth-edition-study-guide-ebook-and-online-course.html


1 The input to DFHLS2WS is a set of control statements governing its

processing and file containing the language structure corresponding to the invocation parameters of a CICS application program. The output is

the WSDL corresponding to the language structure, and a WSBIND

file. This utility is intended for use by an application developer who wishes to expose a program's functionality

as a web service.



1 In this case, the application program is invoked when an HTTP request for its services is received by the CICS

region. The application program sees the request as language structure in

either a CICS container or a COMMAREA (communication area),

which one is governed by the control statements fed into DFHLS2WS. The

application program performs its processing and writes the response

back to the language structure it was invoked with.



1 In either case, whether the CICS application is acting as a web services client or server, the

mapping of data to and from XML is governed by the generated WSBIND file. The message body is wrapped in, and unwrapped from, a SOAP envelope by CICS Web Services plumbing code external to the

application program.https://store.theartofservice.com/itil-2011-foundation-complete-certification-kit-fourth-edition-study-guide-ebook-and-online-course.html


1 The connections between a web service, the WSBIND file, the WSDL, and the CICS transaction requesting or providing the service is done with CICS system level definitions and a

configuration file.



1 Also introduced with CICS TS 3.1 was the capability for CICS applications to

act as HTTP clients. This allowed CICS transactions to participate as clients in a Plain Old XML|POX or

Representational State Transfer|REST conversation.



1 CICS TS can be extended with additional programming features using SupportPacs. For example

SupportPac CA8K introduces support for Atom (standard)|Atom feeds, and SupportPac CA1S adds support for

the PHP scripting language, using the same Java-based PHP engine as Project Zero. Often SupportPac

introduce new technologies into CICS before they are added into the main

product, for example CA8K introduced Atom feeds before it was officially integrated into the product

in CICS TS 4.1


CICS - CICS Family

1 Although when CICS is mentioned, people usually mean CICS

Transaction Server, the CICS Family refers to a portfolio of transaction servers, connectors (called CICS

Transaction Gateway) and CICS Tools.


CICS - CICS Family

1 CICS on distributed platforms - not mainframes - is called IBM TXSeries, which is available on AIX, Microsoft

Windows|Windows, Solaris (Operating System)|Solaris, and HP-UX Operating Systems. CICS is also

available on other Operating Systems, notably IBM i and OS/2. The

z/OS implementation (i.e., CICS Transaction Server for z/OS) is by far

the most popular and significant.https://store.theartofservice.com/itil-2011-foundation-complete-certification-kit-fourth-edition-study-guide-ebook-and-online-course.html

CICS - Programming considerations

1 The modular design of CICS reentrant / reusable control programs meant

that, with judicious pruning, multiple users with multiple applications could be executed on a computer with just

32K of expensive magnetic core physical memory (including the

Operating System)



1 A common technique was to limit the size of individual programs to no

more than 4,096 bytes, or 4K, so that CICS could easily reuse the memory

occupied by any program not currently in use for another program or other application storage needs



1 The efficiency of compiled high-level COBOL and PL/I language programs left much to be desired. Many CICS

application programs continued to be written in assembler language, even

after COBOL and PL/I support became available.



1 Small shops with only one analyst learned CICS optimization very slowly (or not at all).



1 Unfortunately, many of the rules were frequently broken, especially by COBOL programmers who might not

understand the internals of their programs or fail to use the necessary restrictive compile time options. This resulted in non-re-entrant code that

was often unreliable, leading to spurious storage violations and entire

CICS system crashes.https://store.theartofservice.com/itil-2011-foundation-complete-certification-kit-fourth-edition-study-guide-ebook-and-online-course.html


1 Program corruption and CICS control block corruption was a frequent cause of system

downtime



1 These serious shortcomings persisted for multiple new releases of CICS

over a period of more than 20 years. CICS application transactions were

often mission-critical for public utility companies, large banks and other

multi-billion-dollar financial institutions. Top-quality CICS skills

were in high demand and short supply. The complex learning curve was shallow and long. Unqualified novice developers could have a

major negative impact on company operations.



1 Eventually, it became possible to provide a measure of advance

application protection by performing all testing under control of a

monitoring program that also served to provide Test and Debug features.

One such software offering was known as IBM OLIVER (CICS

interactive test/debug)|OLIVER, which prevented application

programs corrupting memory by using Instruction set simulator|instruction set simulation of the

application code, providing partial virtualization.


CICS - Macro-level programming

1 When CICS was first released, it only supported application transaction

programs written in IBM Basic assembly language|IBM 360

Assembler. COBOL and PL/I support were added years later. Because of

the initial assembler orientation, requests for CICS services were made using assembler language Macro instruction|macros. For

example the request to read a record from a file were made by a macro call to the File Control Program of

CICS might look like this:


CICS - Command-level programming

1 During the 1980s, IBM at Hursley produced a half-way house version of

CICS that supported what became known as Command-level CICS. This

release still supported the older programs but introduced a new layer

of execution to the new Command level application programs.


CICS - Command-level programming

1 At execution time, the command-level commands were converted

back using a run-time translator, The EXEC Interface Program, to the old Macro-level call, which was then

executed by the mostly unchanged CICS nucleus programs.


CICS - Run-time conversion

1 The 'Command-level-only' CICS introduced in the early 1990s offered

some advantages over earlier versions of CICS. However, IBM also

dropped support for Macro-level application programs written for earlier versions. This meant that

many application programs had to be converted or completely rewritten to use Command-level EXEC commands

only.https://store.theartofservice.com/itil-2011-foundation-complete-certification-kit-fourth-edition-study-guide-ebook-and-online-course.html

CICS - Run-time conversion

1 It was, however, possible to execute old Macro-level programs using

conversion software such as APT International's Command CICS. This

allowed applications to take advantage of the new features of later versions of CICS while, at the same time, retaining the original

unaltered code base. It is believed that there are still programs running today using this same technology.


CICS - New programming styles

1 CICS Transaction Server Version 2.1 introduced support for Enterprise Java Beans (EJB). CICS Transaction Server Version 2.2 supported the Software Developers Toolkit. CICS

provides the same run-time container as IBM's WebSphere

product family so EJB applications are portable between CICS and

Websphere and there is common tooling for the development and deployment of EJB applications.


CICS - Transactions

1 A CICS transaction is a set of operations that perform a task together. Usually, the

majority of transactions are relatively simple tasks such as requesting an

inventory list or entering a debit or credit to an account. A primary characteristic of a transaction is that it should be atomicity

(database systems)|atomic. On IBM System z servers, CICS easily supports thousands of

transactions per second, making it a mainstay of enterprise computing.


CICS - Transactions

1 CICS applications comprise transactions, which can be written in numerous programming languages, including COBOL, PL/I, C, C++, IBM

Basic assembly language, REXX, and Java.


CICS - Transactions

1 The end user inputs data, which is made accessible to the program by receiving a map

from CICS.


CICS - Example of BMS Map Code

1 Basic Mapping Support defines the screen format through assembler

macros such as the following. This was assembled to generate both the physical map set - a load module in a

CICS load library - and a symbolic map set - a structure definition or DSECT in PL/I, COBOL, assembler,

etc. which was copied into the source program.


CICS - Structure

1 , spread across one or more z/OS system images. Although it processes interactive

transactions, each CICS region may be started as a batch processing|batch address

space with standard Job Control Language|JCL statements: it's a job that runs indefinitely.

Alternatively, each CICS region may be started as a started task. Whether a batch job

or a started task, CICS regions may run for days, weeks, or even months before shutting

down for maintenance (MVS or CICS).


CICS - Components

1 Each CICS region comprises one major task on which every

transaction runs, although certain services such as access to IBM DB2|DB2 data use other tasks (TCBs). Within a region transactions are

Cooperative multitasking#Cooperative_multitaski

ng.2Ftime-sharing|cooperatively multitasked mdash; they are

expected to be well-behaved and yield the CPU rather than wait. CICS services handle this automatically.


CICS - Components

1 Each unique CICS task (computers)|Task or transaction is allocated its own dynamic computer storage|

memory at start-up and subsequent requests for additional memory were

handled by a call to the Storage Control program (part of the CICS

'nucleus' or kernel (computer science)|kernel), which is analogous

to an Operating System.https://store.theartofservice.com/itil-2011-foundation-complete-certification-kit-fourth-edition-study-guide-ebook-and-online-course.html

CICS - Components

1 A CICS system consiste of the online nucleus, batch support programs, and applications

services.


CICS - Nucleus

1 the CICS nucleus consists of a number of

functional modules.


CICS - Support programs

1 In addition to the online functions CICS had several support programs that ran as batch

jobs.



1 * Dump utility - prints formatted

dumps generated by CICS Dump

Management.https://store.theartofservice.com/itil-2011-foundation-complete-certification-kit-fourth-edition-study-guide-ebook-and-online-course.html


1 * Trace utility - formats and prints CICS trace output.



1 * Journal formatting utility - prints a formatted dump of the CICS region in case of error.


CICS - Applications services

1 The following components of CICS support application

development.


CICS - Applications services

1 * EXEC Interface Program - the stub program that converts calls

generated by EXEC CICS commands to calls to CICS functions.


CICS - Pronunciation

1 Different countries have differing pronunciations IBM, 2004, CICS an

introduction, ftp://service.boulder.ibm.com/software/htp/cics/PDF/cics_introduction.pdf


CICS-FM

1 'CICS-FM' is a Canada|Canadian radio station, which broadcasts at 91.7 FM

radio|FM in Greater Sudbury|Sudbury, Ontario. The station airs a country music format, branded as 'KICX 91.7'. The studio and offices

are located at 60 Elm Street, and the station transmits a 50,000 watt

signal from the CBC tower.


CICS-FM - History

1 Owned by Larche Communications, the station was licensed by the Canadian Radio-

television and Telecommunications Commission|CRTC on July 12, 2007.[

http://www.crtc.gc.ca/eng/archive/2007/db2007-229.htm CRTC Decision 2007-229] The format and branding were patterned on Larche's existing CICZ-FM in Midland,

Ontario|Midland, although CICZ's format and brand were moved to sister station CICX-FM

in Orillia before CICS was launched.


CICS-FM - Technical issues

1 CICS-FM may receive some interference from a 100kW FM signal,

WCMU-FM|WCML-FM in Alpena, Michigan. Although Sudbury is well

outside of WCML's normal broadcast range, due to Tropospheric

propagation|tropospheric ducting over Lake Huron the signal has

sometimes reached the Sudbury area strongly enough to be in almost

crystal clear FM stereo.[ http://www.recnet.com/cdbs/fmq.php?facid=9907jaws=0 WCML-FM from

recnet]


IBM OLIVER (CICS interactive test/debug)

1 'OLIVER' (CICS interactive test/debug) was a proprietary testing

and debugging toolkit for interactively testing programs

designed to run on IBM's Customer Information Control System (CICS) on

IBM's System/360/370/390 architecture.


IBM OLIVER (CICS interactive test/debug) - History

1 As a result, errors in application programs frequently caused full CICS dumps and aborted the CICS session

for all users


IBM OLIVER (CICS interactive test/debug) - Technical details

1 * illegal SVC - (CICS applications were not allowed to use any System

call|Operating System calls)



1 * illegal or potentially damaging CICS API requests (e.g. attempts to read into non-

owned memory)



1 :: - All CICS API calls were effectively Shim (computing)|Shimmed by

OLIVER anyhow and checked for validity (If CEDF was also active,

control would pass to it quite naturally while stepping through the

API call).



1 OLIVER additionally provided fully automatic storage protection

features to prevent rogue applications from overwriting storage

occupied by other applications (storage violations, or buffer overflows), OLIVER included

complete and automatic protection for CICS system tables and all other

otherwise unprotected kernel (computer science)|kernel code.


IBM OLIVER (CICS interactive test/debug) - Instruction set simulator

1 The simulation was deliberately limited to CICS application code and EXEC interface code (not the CICS

kernel (computer science)|kernel or Operating System or computer

hardware|hardware), including full instruction trace if required at

machine code level


IBM OLIVER (CICS interactive test/debug) - Non-invasive breakpoints

1 This technique allowed later hardware protected CICS application

programs to be monitored with essentially no change to the OLIVER

Kernel (computing)|kernel code - unlike many of its competitors -

which had used invasive techniques which would no longer work for these programs because of the Operating

System program protection.https://store.theartofservice.com/itil-2011-foundation-complete-certification-kit-fourth-edition-study-guide-ebook-and-online-course.html

CICS Transaction Gateway

1 IBM 'CICS Transaction Gateway' provides secure access to CICS from Java (programming language)|Java,

Java EE, .NET Framework, C (programming language)|C and C++ applications, using Internet protocols

(for example TCP/IP).



1 CICS Transaction Gateway also includes the same capabilities as IBM CICS Universal

Client.



1 There are three products in the CICS Transaction Gateway

family:



1 * CICS Transaction Gateway for

Multiplatforms



1 Further information about CICS Transaction Gateway is available to

read [ http://www.ibm.com/software/product

s/us/en/cics-ctg online].


WebSphere Optimized Local Adapters - Overview of CICS support

1 The Optimized Local Adapters are implemented in CICS as a Task

Related User Exit (TRUE). This is what provides the essential

connectivity from CICS cross memory to the WAS z/OS address space.



1 The target program in CICS must be able to be invoked with a LINK call



1 The OLA programming interface module library data set must be

concatenated to the CICS region's DFHRPL DD statement.



1 The following picture summarizes the WOLA CICS support for transaction propagation and security assertion:


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CICS