Intro to CICS

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CICS : 

CICS IBM’s Customer Information Control System

CICS Programming Languages : 

CICS Programming Languages Assembler COBOL PL/I Rexx C/C++ JAVA

Common types of on-line systems: : 

Common types of on-line systems: Menu Inquiry Data entry

On-line system considerations: : 

On-line system considerations: Performance File integrity Security Ease of use. Data integrity

Program Design : 

Program Design Critical! Can save hours (days!) PSEUDO-CONVERSATIONAL (different!) Event Driven - Major Functions

Pseudo-Conversational : 

Pseudo-Conversational An on-line program that actually ended while appearing to wait for a response. Single-user systems are ‘conversational’ System waits for operator to enter data Single user system - nothing else to do Multi-user system can’t waste the time 3270 screen handles operator activity

Pseudo-Conversational : 

Pseudo-Conversational Conversational program remains in storage during entire interaction. Pseudo-conversational program only in storage for a few seconds each action. Many more users can be processed Storage used more efficiently Minor complication to programs!

Pseudo-Conversational : 

Pseudo-Conversational Terminal handles operator entry Attention Key signals CICS screen ready Enter, PF, PA, or Clear Key - (Event) CICS reloads program (Virtual Storage) Program start at BEGINNING every time You must keep up with where user is User unaware that program restarted

PSEUDOCONVERSATIONAL PROGRAMMING: : 

PSEUDOCONVERSATIONAL PROGRAMMING:

CICS Table Entries : 

CICS Table Entries PCT = Program Control Table TRANS-ID assigned to Program PPT = Processing Program Table (2) COBOL Program Mapset - Assembler Program FCT = File Control Table FILE(s) used by Program Usually done by Systems Programmer

CICS Service Diagram : 

CICS Service Diagram Terminal Control (VTAM,SNA,TCP/IP) Basic Mapping Support Terminal User Application Programming Interface Application Program Maps File Control SQL DL/I VSAM DB2 IMS OS/390 CICS

CICS Program Invocation : 

CICS Program Invocation User Enters TRANS-ID CICS finds TRANS-ID in PCT to get program name CICS finds program name in PPT CICS loads program into memory/ starts program CICS runs program in address space TRANS-ID = Transaction Identifier PCT = Program Control Table PPT= Processing Program Table

CICS Example - Screen 1 : 

CICS Example - Screen 1

CICS Example - Screen 2 : 

CICS Example - Screen 2

CICS Example - Screen 3 : 

CICS Example - Screen 3

CICS Example - Screen 4 : 

CICS Example - Screen 4

Creating a BMS MAPSET : 

Creating a BMS MAPSET 3270 is FIELD oriented display Screen divided into user defined fields Each field has CHARACTERISTICS Determined by ATTRIBUTE BYTES (First character of each field!) Displayed as a space, but NOT available

Create the BMS Mapset : 

Create the BMS Mapset Defines the MAP(s) used by program MAP provides for screen formatting MAPSET is group of screens (1 or more) Normally only one MAP per MAPSET Only three macro’s used to create MAP Usually a ‘Screen Generator’ is used

CICS Screen : 

CICS Screen Basic Mapping Support (BMS) or a Screen painter used to develop BMS uses assembler macros to define screen layout(s) DFH = Always means CICS DFHMSD = mapset descriptor (one per mapset) DFHMDI = map descriptor initiator (one per map) DFHMDF = map descriptor field (one for each map field)

Define a Mapset : 

Define a Mapset To define the mapset. name DFHSMD TYPE=(type of mapset), MODE=how map is used, CTRL=FREEKB, LANG=language, TIOAPFX=YES, STORAGE = AUTO To end a mapset definition DFHSMD TYPE=FINAL

Example Mapset Definition : 

Example Mapset Definition MENU013 DFHMSD TYPE=&SYSPARM, MODE=INOUT, TERM=ALL, LANG=COBOL, TIOAPFX=YES, CTRL=FREEKB, BASE=MAPS Maps and field definitions go here DFHMSD TYPE=FINAL END

Define a Map : 

Define a Map MENU013 DFHMDI SIZE=(24,80), LINE=1, COLUMN=1

Define Fields : 

Define Fields DFHMDF POS=(7,10),LENGTH=10,INITIAL='LAST NAME:', ATTRB=ASKIP LNAME DFHMDF POS=(7,21),LENGTH=20,ATTRB=(UNPROT,IC) MESSGE DFHMDF POS=(5,10),LENGTH=64,ATTRB=(PROT)

ATTRB Parameter : 

ATTRB Parameter BRT High intensity display NORM Normal intensity DRK Not displayed (Hidden) PROT Protected – no data keyed UNPROT Data may be keyed in IC Initial cursor position FSET MDT set ON for field

Protection Attribute : 

Protection Attribute Protected – user can’t key data in field Unprotected – user allowed to key data Auto-Skip – cursor skips to next field Used to mark end of data entry field Cursor automatically moves to next field

Intensity Attribute : 

Intensity Attribute Normal – shown normal intensity Bright – shown in high intensity No-display – not shown (background) Used for password entry Also used to ‘hide’ data on screen

Coding a BMS Mapset : 

Coding a BMS Mapset Only need two Assembler commands PRINT NOGEN DFHMSD – Map Set Definition DFHMDI – Map Definition DFHMDF – Field (Attribute byte) Definition DFHMDI – Map Definition DFHMDF – Field (Attribute byte) Definition END

More terminology : 

More terminology PHYSICAL MAP – load module Result of Assembly Contains table of screen locations of data Also contains attributes of each field SYMBOLIC MAP – Copy library member Result of Assembly Usually used in COBOL program You can create your own – if careful!

The Symbolic Map : 

The Symbolic Map Copy member created by Assembly Use COPY statement in COBOL Maximum of 7 character field names MAPGEN adds the 8th (last) character Fine for Assembler–Marginal in COBOL You can code your own – if careful!

Symbolic Map Suffix List : 

Symbolic Map Suffix List I The INPUT data field O The OUTPUT data field (Same loc I) L Binary Halfword-S9(4) COMP that contains data returned in input field F Char w/’80’ if field was cleared A Char w/attrb for output (Same loc F) C/H Used for Color and/or Highlighting

Sample CICS Scenario : 

Sample CICS Scenario Transaction ID Entered Looked up in PCT - Program loaded Program displays initial map and ends User enters data and hits ‘Enter’ key Program reloaded Receives data from screen Processes data Sends response back to screen Returns to CICS

CICS Input/Output : 

CICS Input/Output CICS handles all I/O Treat screen as simple file (one record) Can Read Screen – RECEIVE MAP Can Write Screen – SEND MAP Can Return to CICS with ID of Program to execute next time user keys AID key Return without TRANS-ID, Exits to CICS

Send A Map : 

Send A Map * SEND MAP FIRST TIME IN. * IF EIBCALEN = 0 MOVE 'MENU013' TO MAP-NAME PERFORM SEND-MAP-MAPONLY PERFORM RETURN-TRANSID END-IF SEND-MAP-MAPONLY. EXEC CICS SEND MAP(MAP-NAME) MAPONLY ERASE NOHANDLE END-EXEC EVALUATE EIBRESP WHEN DFHRESP(NORMAL)

Receive a Map : 

Receive a Map * * RECEIVE MAP * EXEC CICS RECEIVE MAP(MAP-NAME) INTO(MAPS) NOHANDLE END-EXEC EVALUATE EIBRESP WHEN DFHRESP(NORMAL) CONTINUE WHEN DFHRESP(MAPFAIL)

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