Editing CICS (section)

==Transactions==
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 Z]] servers, CICS easily supports thousands of transactions per second, making it a mainstay of enterprise computing.

CICS applications comprise transactions, which can be written in numerous [[programming language]]s, including COBOL, PL/I, C, C++, IBM Basic Assembly Language, [[Rexx]], and Java.

Each CICS program is initiated using a transaction identifier. CICS screens are usually sent as a construct called a map, a module created with [[Basic Mapping Support]] (BMS) assembler macros or third-party tools. CICS [[panel (computer software)|screens]] may contain text that is highlighted, has different colors, and/or blinks depending on the terminal type used. An example of how a map can be sent through COBOL is given below. The end user inputs data, which is made accessible to the program by receiving a map from CICS.

<syntaxhighlight lang="cobolfree">
 EXEC CICS
     RECEIVE MAPSET('LOSMATT') MAP('LOSATT') INTO(OUR-MAP)
 END-EXEC.
</syntaxhighlight>

For technical reasons, the arguments to some command parameters must be quoted and some must not be quoted, depending on what is being referenced. Most programmers will code out of a reference book until they get the "hang" or concept of which arguments are quoted, or they'll typically use a "canned template" where they have example code that they just copy and paste, then edit to change the values.

===Example of BMS Map Code===
Basic Mapping Support defines the screen format through assembler macros such as the following.  This was assembled to generate both the ''physical map set''{{snd}} a load module in a CICS load library{{snd}} and a ''symbolic map set''{{snd}} a structure definition or ''DSECT'' in PL/I, COBOL, assembler, etc. which was copied into the source program.<ref>{{cite web|last=IBM Corporation|title=Basic mapping support|url=http://publib.boulder.ibm.com/infocenter/cicsts/v2r3/index.jsp?topic=/com.ibm.cics.ts23.doc/dfhp3/dfhp370.htm|archive-url=https://archive.today/20130103084403/http://publib.boulder.ibm.com/infocenter/cicsts/v2r3/index.jsp?topic=/com.ibm.cics.ts23.doc/dfhp3/dfhp370.htm|url-status=dead|archive-date=2013-01-03|work=CICS Information Center}}</ref>

<syntaxhighlight lang="cobolfree">
 LOSMATT DFHMSD TYPE=MAP,                                               X
                MODE=INOUT,                                             X
                TIOAPFX=YES,                                            X
                TERM=3270-2,                                            X
                LANG=COBOL,                                             X
                MAPATTS=(COLOR,HILIGHT),                                X
                DSATTS=(COLOR,HILIGHT),                                 X
                STORAGE=AUTO,                                           X
                CTRL=(FREEKB,FRSET)
 *
 LOSATT  DFHMDI SIZE=(24,80),                                           X
                LINE=1,                                                 X
                COLUMN=1
 *
 LSSTDII DFHMDF POS=(1,01),                                             X
                LENGTH=04,                                              X
                COLOR=BLUE,                                             X
                INITIAL='MQCM',                                         X
                ATTRB=PROT
 *
         DFHMDF POS=(24,01),                                            X
                LENGTH=79,                                              X
                COLOR=BLUE                                              X
                ATTRB=ASKIP,                                            X
                INITIAL='PF7-          8-           9-          10-     X
                    11-            12-CANCEL'
 *
           DFHMSD   TYPE=FINAL
           END
</syntaxhighlight>