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COBOL Debugging Programs › Use Variable-Change Breakpoints to Detect Changing Values › Set a Variable-Change Breakpoint

Set a Variable-Change Breakpoint

A quick way to set a variable-change breakpoint is from the point in the listing where it is defined. In the following example, you will set a variable-change breakpoint on TSQ-TERMID.

To set a variable-change breakpoint

  1. Position the listing at the definition for TSQ-TERMID by typing L TSQ-TERMID in the Command line field, and press Enter. 
       CA InterTest for CICS V9.1   - PROTSYM FILE  SOURCE LISTING DISPLAY          
COMMAND ===> L TSQ-TERMID                                                       
Program= COBDEMO  Option #       Stmt #                             Margin= 01  
                                        Search=                                 
OPTS 1 Proc div  2 Work-stor 3 Link sect  4 D-map      5 Clst/Pmap More:   +    
     6 Data xref 7 Proc xref 8 Err msgs   9 Srch fwd  10 Srch bwd               
PFKS 1 Help      2           3 End        4 Profile    5 Monitor    6 Menu      
     7 Backward  8 Forward   9           10           11           12 Status    
------------------------------------------------------------------------------- 
      YEARWINDOW(1900)                                                          
      ZWB                                                                       
   000001 ID DIVISION.                                                          
   000002 PROGRAM-ID. COBDEMO.                                                  
   000003 ENVIRONMENT DIVISION.                                                 
   000004 DATA DIVISION.                                                        
 _ 000005 WORKING-STORAGE SECTION.   
.
.
.
  2. The listing is then positioned at the definition for the TSQ-TERMID. Type v to the left of the statement defining the TSQ-TERMID field, position the cursor on the TSQ-TERMID field, and press Enter. 
       CA InterTest for CICS V9.1   - PROTSYM FILE  SOURCE LISTING DISPLAY         
COMMAND ===>                                                                   
Program= COBDEMO  Option #       Stmt #                             Margin= 01 
                                        Search=                                
OPTS 1 Proc div  2 Work-stor 3 Link sect  4 D-map      5 Clst/Pmap More:   +   
     6 Data xref 7 Proc xref 8 Err msgs   9 Srch fwd  10 Srch bwd              
PFKS 1 Help      2           3 End        4 Profile    5 Monitor    6 Menu     
     7 Backward  8 Forward   9           10           11           12 Status   
-------------------------------------------------------------------------------
 _ 000027 01  TSQ-NAME.                                                        
 _ 000028     03 TSQ-TRANID            PIC XXXX.                               
 v 000029     03 TSQ-TERMID            PIC XXXX.                               
 _ 000030 01  TASK-STRUCTURE.                                                  
 _ 000031     03 TASK-CNTL             PIC X(4)  VALUE 'CNTL'.                 
 _ 000032     03 TASK-PROTCPF          PIC X(8)  VALUE 'PROTCPF'.              
 _ 000033     03 TASK-PROTHLF          PIC X(8)  VALUE 'PROTHLF'.              
 _ 000034     03 TASK-SWITCH           PIC X. 
.
  3. Type the DEMC transaction. The following breakpoint displays:Type the DEMC transaction. The following breakpoint displays: 
       CA InterTest for CICS V9.1   - PROTSYM FILE   COND  BEFORE  BREAKPOINT    
COMMAND ===>                                                                  
Program= COBDEMO  Option #       Stmt #                             Margin= 01
                                        Search=                               
-- More:   + ----------------------------------- PFKS 19 Backward 20 Forward -
 _____ DMAP04AI                        | .....................................
 _____ DMAPBEGI                        | ............                         
 _____ DMAPASRI                        | ............                         
 _____ DMAPSUMI                        | ............                         
 _____ DMAPENDI                        | .....................................
 _____ DMAP00I                         | .....................................
---------+--------------------------------------------------------------------
 _ 000353     MOVE EIBTRMID TO TSQ-TERMID.                                    
   000354*** THIS CODE INITIALIZES THE MAPS BECAUSE COBOL2 DOESN'T ***        
 V    ==>     MOVE LOW-VALUES TO DMAP04AI                                     
     ==>                                                                      
     ==> CAIN3630 Conditional breakpoint    requested at offset .ANY          
     ==> IF='TSQ-TERMID'.NE.'TSQ-TERMID'                                      
     ==>                                                                      
 _ 000356                  DMAPBEGI                                           
 _ 000357                  DMAPASRI                                           
 _ 000358                  DMAPSUMI                                           
 _ 000359                  DMAPENDI                                           
 _ 000360                  DMAP00I

    Note: the listing is positioned on the statement following that which actually changed TSQ-TERMID, because the field is examined at the beginning of each new COBOL statement.

    The listing is positioned on the statement following that which actually changed TSQ-TERMID, because the field is examined at the beginning of each new COBOL statement.

    A variable-change-breakpoint may be set any time during execution, or from a listing of your program before execution begins. You may find it useful to also set a static keep on the field which you are interested in watching for a change. In this way you will be able see how it changed automatically each time a variable change breakpoint occurs.

    Each variable change breakpoint is identified by the abbreviation VBP on the Status Report and Monitoring Status display.

    Variable-change breakpoints are actually a special type of conditional breakpoint. CA InterTest for CICS checks for the condition at any statement, as shown in the following example:

    IF 'data-item'.NE.data-item'

    which means:

    IF data-item (current) NOT EQUAL TO data-item (value when breakpoint set)

    To explore additional ways to set and use conditional breakpoints, see the later chapters in this primer.