MainframeMaster

COBOL Tutorial

COBOL ERROR Handling

ERROR handling represents a fundamental component of robust application development in COBOL, serving as the primary mechanism for managing exceptions, processing error conditions, and implementing recovery procedures. This concept embodies defensive programming principles by providing comprehensive error detection capabilities, enabling sophisticated exception management processes, and supporting the development of resilient applications that can gracefully handle unexpected conditions and maintain operational integrity.

Basic ERROR Handling

cobol
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
IDENTIFICATION DIVISION.
PROGRAM-ID. ERROR-HANDLING-DEMO.
 
DATA DIVISION.
WORKING-STORAGE SECTION.
01  ERROR-MANAGEMENT-SYSTEM.
    05  ERROR-STATUS            PIC X VALUE 'N'.
        88  ERROR-OCCURRED      VALUE 'Y'.
        88  NO-ERROR            VALUE 'N'.
    05  ERROR-CODE              PIC 9(4) VALUE 0.
    05  ERROR-MESSAGE           PIC X(80).
    05  ERROR-SEVERITY          PIC X(8).
        88  SEVERITY-INFO       VALUE 'INFO'.
        88  SEVERITY-WARNING    VALUE 'WARNING'.
        88  SEVERITY-ERROR      VALUE 'ERROR'.
        88  SEVERITY-CRITICAL   VALUE 'CRITICAL'.
 
01  FILE-ERROR-HANDLING.
    05  FILE-STATUS-CODE        PIC XX.
        88  FILE-SUCCESS        VALUE '00'.
        88  FILE-NOT-FOUND      VALUE '35'.
        88  FILE-PERMISSION     VALUE '37'.
        88  FILE-DISK-FULL      VALUE '34'.
    05  FILE-ERROR-COUNT        PIC 9(5) VALUE 0.
    05  RECOVERY-ATTEMPTS       PIC 9(2) VALUE 0.
 
PROCEDURE DIVISION.
MAIN-PROCESSING.
    PERFORM INITIALIZE-ERROR-SYSTEM
    PERFORM DEMONSTRATE-FILE-ERROR-HANDLING
    PERFORM DEMONSTRATE-ARITHMETIC-ERROR-HANDLING
    PERFORM DEMONSTRATE-CUSTOM-ERROR-HANDLING
    PERFORM DISPLAY-ERROR-STATISTICS
    STOP RUN.
 
INITIALIZE-ERROR-SYSTEM.
    SET NO-ERROR TO TRUE
    MOVE 0 TO ERROR-CODE
    MOVE SPACES TO ERROR-MESSAGE
    SET SEVERITY-INFO TO TRUE
    DISPLAY 'Error handling system initialized'.
 
DEMONSTRATE-FILE-ERROR-HANDLING.
    DISPLAY 'Demonstrating file error handling...'
    
    *> Simulate file operation with error handling
    MOVE '35' TO FILE-STATUS-CODE  *> File not found
    
    PERFORM PROCESS-FILE-STATUS
    
    IF ERROR-OCCURRED
        PERFORM HANDLE-FILE-ERROR
    END-IF.
 
PROCESS-FILE-STATUS.
    EVALUATE FILE-STATUS-CODE
        WHEN '00'
            SET NO-ERROR TO TRUE
            DISPLAY 'File operation successful'
        WHEN '35'
            SET ERROR-OCCURRED TO TRUE
            MOVE 1001 TO ERROR-CODE
            MOVE 'File not found' TO ERROR-MESSAGE
            SET SEVERITY-ERROR TO TRUE
        WHEN '37'
            SET ERROR-OCCURRED TO TRUE
            MOVE 1002 TO ERROR-CODE
            MOVE 'Permission denied' TO ERROR-MESSAGE
            SET SEVERITY-ERROR TO TRUE
        WHEN '34'
            SET ERROR-OCCURRED TO TRUE
            MOVE 1003 TO ERROR-CODE
            MOVE 'Disk full' TO ERROR-MESSAGE
            SET SEVERITY-CRITICAL TO TRUE
        WHEN OTHER
            SET ERROR-OCCURRED TO TRUE
            MOVE 1999 TO ERROR-CODE
            MOVE 'Unknown file error' TO ERROR-MESSAGE
            SET SEVERITY-ERROR TO TRUE
    END-EVALUATE.
 
HANDLE-FILE-ERROR.
    ADD 1 TO FILE-ERROR-COUNT
    
    DISPLAY 'File Error Details:'
    DISPLAY 'Error Code: ' ERROR-CODE
    DISPLAY 'Error Message: ' ERROR-MESSAGE
    DISPLAY 'Severity: ' ERROR-SEVERITY
    
    IF SEVERITY-CRITICAL
        DISPLAY 'Critical error - terminating program'
        STOP RUN
    END-IF
    
    PERFORM ATTEMPT-ERROR-RECOVERY.
 
ATTEMPT-ERROR-RECOVERY.
    ADD 1 TO RECOVERY-ATTEMPTS
    
    IF RECOVERY-ATTEMPTS < 3
        DISPLAY 'Attempting recovery, attempt: ' RECOVERY-ATTEMPTS
        *> Implement recovery logic here
        DISPLAY 'Recovery attempt completed'
    ELSE
        DISPLAY 'Maximum recovery attempts reached'
        DISPLAY 'Manual intervention required'
    END-IF.
 
DEMONSTRATE-ARITHMETIC-ERROR-HANDLING.
    DISPLAY 'Demonstrating arithmetic error handling...'
    
    PERFORM SAFE-DIVISION
    PERFORM SAFE-MULTIPLICATION.
 
SAFE-DIVISION.
    *> Simulate division by zero protection
    COMPUTE ERROR-CODE = 100 / 0
        ON SIZE ERROR
            SET ERROR-OCCURRED TO TRUE
            MOVE 2001 TO ERROR-CODE
            MOVE 'Division by zero attempted' TO ERROR-MESSAGE
            SET SEVERITY-ERROR TO TRUE
            DISPLAY 'Arithmetic Error: ' ERROR-MESSAGE
        NOT ON SIZE ERROR
            DISPLAY 'Division completed successfully'
    END-COMPUTE.
 
SAFE-MULTIPLICATION.
    *> Simulate overflow protection
    COMPUTE ERROR-CODE = 999999 * 999999
        ON SIZE ERROR
            SET ERROR-OCCURRED TO TRUE
            MOVE 2002 TO ERROR-CODE
            MOVE 'Arithmetic overflow occurred' TO ERROR-MESSAGE
            SET SEVERITY-WARNING TO TRUE
            DISPLAY 'Arithmetic Warning: ' ERROR-MESSAGE
        NOT ON SIZE ERROR
            DISPLAY 'Multiplication completed successfully'
    END-COMPUTE.
 
DEMONSTRATE-CUSTOM-ERROR-HANDLING.
    DISPLAY 'Demonstrating custom error handling...'
    
    PERFORM VALIDATE-BUSINESS-RULES
    PERFORM HANDLE-CUSTOM-ERRORS.
 
VALIDATE-BUSINESS-RULES.
    *> Simulate business rule validation
    SET ERROR-OCCURRED TO TRUE
    MOVE 3001 TO ERROR-CODE
    MOVE 'Business rule violation: Invalid customer type' TO ERROR-MESSAGE
    SET SEVERITY-WARNING TO TRUE.
 
HANDLE-CUSTOM-ERRORS.
    IF ERROR-OCCURRED
        DISPLAY 'Custom Error Details:'
        DISPLAY 'Error Code: ' ERROR-CODE
        DISPLAY 'Error Message: ' ERROR-MESSAGE
        DISPLAY 'Severity: ' ERROR-SEVERITY
        
        PERFORM LOG-ERROR-TO-FILE
        PERFORM NOTIFY-ADMINISTRATOR
    END-IF.
 
LOG-ERROR-TO-FILE.
    DISPLAY 'Logging error to file...'
    DISPLAY 'Error logged with timestamp'.
 
NOTIFY-ADMINISTRATOR.
    IF SEVERITY-CRITICAL OR SEVERITY-ERROR
        DISPLAY 'Administrator notification sent'
    END-IF.
 
DISPLAY-ERROR-STATISTICS.
    DISPLAY 'Error Handling Statistics:'
    DISPLAY 'File errors: ' FILE-ERROR-COUNT
    DISPLAY 'Recovery attempts: ' RECOVERY-ATTEMPTS
    DISPLAY 'Last error code: ' ERROR-CODE.

Best Practices and FAQ