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COBOL Tutorial

COBOL GOBACK Statement

The GOBACK statement represents a modern and versatile program control return mechanism within COBOL programming environments, serving as the primary specification for returning control from subprograms to calling programs or terminating main program execution with clean resource management. This statement embodies the principles of structured program termination by providing consistent return behavior across different program contexts, enabling reliable inter-program communication patterns, and supporting efficient program lifecycle management while maintaining compatibility with modern COBOL standards and ensuring predictable program flow control in enterprise applications that require robust modular programming architectures and reliable program termination sequences with proper resource cleanup and state management.

Syntax and Usage

GOBACK Statement Syntax
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GOBACK
 
*> In main program - terminates program
*> In subprogram - returns to calling program
 
*> Examples:
GOBACK
IF ERROR-CONDITION
    GOBACK
END-IF
Program Control
Return Mechanism
Modern Practice

Basic GOBACK Examples

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IDENTIFICATION DIVISION.
PROGRAM-ID. MAIN-PROGRAM.
 
DATA DIVISION.
WORKING-STORAGE SECTION.
01  CALCULATION-RESULT      PIC 9(7)V99.
01  ERROR-CODE              PIC 9(3).
01  VALIDATION-STATUS       PIC X.
 
PROCEDURE DIVISION.
MAIN-PROCESSING.
    DISPLAY 'Starting main program...'
    
    *> Call subprogram for validation
    CALL 'VALIDATE-INPUT' USING VALIDATION-STATUS
    
    IF VALIDATION-STATUS = 'N'
        DISPLAY 'Validation failed - terminating'
        GOBACK
    END-IF
    
    *> Call subprogram for calculation
    CALL 'CALCULATE-VALUES' USING CALCULATION-RESULT ERROR-CODE
    
    IF ERROR-CODE NOT = 0
        DISPLAY 'Calculation error: ' ERROR-CODE
        GOBACK
    END-IF
    
    DISPLAY 'Main program completed successfully'
    DISPLAY 'Result: ' CALCULATION-RESULT
    GOBACK.
 
*> Subprogram demonstrating GOBACK usage
IDENTIFICATION DIVISION.
PROGRAM-ID. VALIDATE-INPUT.
 
DATA DIVISION.
LINKAGE SECTION.
01  VALIDATION-RESULT       PIC X.
 
PROCEDURE DIVISION USING VALIDATION-RESULT.
VALIDATION-LOGIC.
    DISPLAY 'Performing input validation...'
    
    *> Simulate validation process
    MOVE 'Y' TO VALIDATION-RESULT
    
    *> Simulate validation failure condition
    IF FUNCTION RANDOM < 0.2
        MOVE 'N' TO VALIDATION-RESULT
        DISPLAY 'Validation failed - invalid input detected'
        GOBACK
    END-IF
    
    DISPLAY 'Validation successful'
    GOBACK.
 
END PROGRAM VALIDATE-INPUT.
 
*> Another subprogram with error handling
IDENTIFICATION DIVISION.
PROGRAM-ID. CALCULATE-VALUES.
 
DATA DIVISION.
WORKING-STORAGE SECTION.
01  TEMP-RESULT             PIC 9(9)V99.
01  DIVISOR                 PIC 9(3) VALUE 100.
 
LINKAGE SECTION.
01  RESULT-VALUE            PIC 9(7)V99.
01  ERROR-STATUS            PIC 9(3).
 
PROCEDURE DIVISION USING RESULT-VALUE ERROR-STATUS.
CALCULATION-LOGIC.
    MOVE 0 TO ERROR-STATUS
    
    *> Simulate complex calculation
    COMPUTE TEMP-RESULT = FUNCTION RANDOM * 1000000
    
    *> Check for overflow
    IF TEMP-RESULT > 99999.99
        MOVE 101 TO ERROR-STATUS
        DISPLAY 'Error: Calculation overflow'
        GOBACK
    END-IF
    
    *> Check for division by zero (simulated)
    IF DIVISOR = 0
        MOVE 102 TO ERROR-STATUS
        DISPLAY 'Error: Division by zero'
        GOBACK
    END-IF
    
    DIVIDE TEMP-RESULT BY DIVISOR GIVING RESULT-VALUE
    DISPLAY 'Calculation completed: ' RESULT-VALUE
    GOBACK.
 
END PROGRAM CALCULATE-VALUES.
 
END PROGRAM MAIN-PROGRAM.

Key Features and Benefits

Universal Return
  • • Works in main and subprograms
  • • Consistent behavior across contexts
  • • Modern COBOL standard compliance
  • • Clean program termination
Simplified Control Flow
  • • Single statement for returns
  • • Automatic resource cleanup
  • • Error handling integration
  • • Structured program design

Interactive Tutorial

Hands-On Exercise: Modular Program Design
Practice using GOBACK for effective program control and error handling

Exercise 1: Error Handling with GOBACK

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IDENTIFICATION DIVISION.
PROGRAM-ID. FILE-PROCESSOR.
 
DATA DIVISION.
LINKAGE SECTION.
01 FILE-NAME PIC X(20).
01 PROCESS-STATUS PIC 9(3).
 
PROCEDURE DIVISION USING FILE-NAME PROCESS-STATUS.
    MOVE 0 TO PROCESS-STATUS
    
    *> Validate file name
    IF FILE-NAME = SPACES
        MOVE 001 TO PROCESS-STATUS
        DISPLAY 'Error: File name is empty'
        GOBACK
    END-IF
    
    *> Simulate file processing
    DISPLAY 'Processing file: ' FILE-NAME
    
    *> Simulate file not found
    IF FILE-NAME(1:4) = 'TEMP'
        MOVE 002 TO PROCESS-STATUS
        DISPLAY 'Error: Temporary files not allowed'
        GOBACK
    END-IF
    
    DISPLAY 'File processed successfully'
    GOBACK.

Exercise 2: Multi-level Program Structure

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IDENTIFICATION DIVISION.
PROGRAM-ID. BUSINESS-LOGIC.
 
PROCEDURE DIVISION.
MAIN-LOGIC.
    CALL 'INITIALIZE-SYSTEM'
    CALL 'PROCESS-TRANSACTIONS'
    CALL 'GENERATE-REPORTS'
    GOBACK.
 
IDENTIFICATION DIVISION.
PROGRAM-ID. INITIALIZE-SYSTEM.
 
PROCEDURE DIVISION.
    DISPLAY 'System initialization...'
    
    *> Check system prerequisites
    PERFORM CHECK-ENVIRONMENT
    PERFORM LOAD-CONFIGURATION
    
    DISPLAY 'System ready'
    GOBACK.
 
CHECK-ENVIRONMENT.
    *> Environment validation
    CONTINUE.
 
LOAD-CONFIGURATION.
    *> Configuration loading
    CONTINUE.
 
END PROGRAM INITIALIZE-SYSTEM.

Advanced GOBACK Patterns

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IDENTIFICATION DIVISION.
PROGRAM-ID. ADVANCED-GOBACK-DEMO.
 
DATA DIVISION.
WORKING-STORAGE SECTION.
01  SYSTEM-STATE.
    05  INITIALIZATION-COMPLETE PIC X VALUE 'N'.
    05  PROCESSING-ACTIVE       PIC X VALUE 'N'.
    05  ERROR-RECOVERY-MODE     PIC X VALUE 'N'.
 
01  OPERATION-COUNTERS.
    05  SUCCESSFUL-OPERATIONS   PIC 9(5) VALUE 0.
    05  FAILED-OPERATIONS       PIC 9(5) VALUE 0.
    05  TOTAL-OPERATIONS        PIC 9(5) VALUE 0.
 
01  WS-COUNTER                  PIC 9(3).
01  WS-RESULT-CODE              PIC 9(2).
 
PROCEDURE DIVISION.
MAIN-CONTROLLER.
    PERFORM SYSTEM-STARTUP
    
    IF INITIALIZATION-COMPLETE = 'Y'
        PERFORM BUSINESS-PROCESSING
    ELSE
        DISPLAY 'System startup failed'
        GOBACK
    END-IF
    
    PERFORM SYSTEM-SHUTDOWN
    
    DISPLAY 'Operations Summary:'
    DISPLAY 'Total: ' TOTAL-OPERATIONS
    DISPLAY 'Successful: ' SUCCESSFUL-OPERATIONS
    DISPLAY 'Failed: ' FAILED-OPERATIONS
    
    GOBACK.
 
SYSTEM-STARTUP.
    CALL 'DATABASE-CONNECT' USING INITIALIZATION-COMPLETE
    
    IF INITIALIZATION-COMPLETE = 'N'
        DISPLAY 'Database connection failed'
        GOBACK
    END-IF
    
    CALL 'LOAD-BUSINESS-RULES' USING INITIALIZATION-COMPLETE
    
    IF INITIALIZATION-COMPLETE = 'N'
        DISPLAY 'Business rules loading failed'
        GOBACK
    END-IF.
 
BUSINESS-PROCESSING.
    MOVE 'Y' TO PROCESSING-ACTIVE
    
    PERFORM VARYING WS-COUNTER FROM 1 BY 1 UNTIL WS-COUNTER > 100
        ADD 1 TO TOTAL-OPERATIONS
        CALL 'PROCESS-TRANSACTION' USING WS-COUNTER WS-RESULT-CODE
        
        IF WS-RESULT-CODE = 0
            ADD 1 TO SUCCESSFUL-OPERATIONS
        ELSE
            ADD 1 TO FAILED-OPERATIONS
            
            *> Emergency stop if too many failures
            IF FAILED-OPERATIONS > 10
                DISPLAY 'Too many failures - stopping processing'
                MOVE 'N' TO PROCESSING-ACTIVE
                EXIT PERFORM
            END-IF
        END-IF
    END-PERFORM.
 
SYSTEM-SHUTDOWN.
    MOVE 'N' TO PROCESSING-ACTIVE
    CALL 'DATABASE-DISCONNECT'
    CALL 'CLEANUP-RESOURCES'.
 
*> Database connection subprogram
IDENTIFICATION DIVISION.
PROGRAM-ID. DATABASE-CONNECT.
 
DATA DIVISION.
WORKING-STORAGE SECTION.
01  CONNECTION-ATTEMPTS      PIC 9(2) VALUE 0.
01  MAX-ATTEMPTS             PIC 9(2) VALUE 3.
 
LINKAGE SECTION.
01  CONNECTION-STATUS        PIC X.
 
PROCEDURE DIVISION USING CONNECTION-STATUS.
CONNECTION-LOGIC.
    MOVE 'N' TO CONNECTION-STATUS
    
    PERFORM VARYING CONNECTION-ATTEMPTS FROM 1 BY 1 
        UNTIL CONNECTION-ATTEMPTS > MAX-ATTEMPTS
           OR CONNECTION-STATUS = 'Y'
        
        DISPLAY 'Connection attempt ' CONNECTION-ATTEMPTS
        
        *> Simulate connection logic
        IF FUNCTION RANDOM > 0.3
            MOVE 'Y' TO CONNECTION-STATUS
            DISPLAY 'Database connected successfully'
            GOBACK
        ELSE
            DISPLAY 'Connection failed, retrying...'
        END-IF
    END-PERFORM
    
    IF CONNECTION-STATUS = 'N'
        DISPLAY 'All connection attempts failed'
    END-IF
    
    GOBACK.
 
END PROGRAM DATABASE-CONNECT.
 
*> Transaction processing subprogram
IDENTIFICATION DIVISION.
PROGRAM-ID. PROCESS-TRANSACTION.
 
DATA DIVISION.
LINKAGE SECTION.
01  TRANSACTION-ID           PIC 9(5).
01  RESULT-CODE              PIC 9(3).
 
PROCEDURE DIVISION USING TRANSACTION-ID RESULT-CODE.
TRANSACTION-LOGIC.
    MOVE 0 TO RESULT-CODE
    
    *> Validate transaction ID
    IF TRANSACTION-ID = 0
        MOVE 001 TO RESULT-CODE
        DISPLAY 'Invalid transaction ID'
        GOBACK
    END-IF
    
    *> Simulate processing
    IF FUNCTION MOD(TRANSACTION-ID, 10) = 0
        MOVE 002 TO RESULT-CODE
        DISPLAY 'Transaction ' TRANSACTION-ID ' failed validation'
        GOBACK
    END-IF
    
    *> Successful processing
    DISPLAY 'Transaction ' TRANSACTION-ID ' processed successfully'
    GOBACK.
 
END PROGRAM PROCESS-TRANSACTION.
 
*> Resource cleanup subprogram
IDENTIFICATION DIVISION.
PROGRAM-ID. CLEANUP-RESOURCES.
 
PROCEDURE DIVISION.
CLEANUP-LOGIC.
    DISPLAY 'Cleaning up temporary files...'
    DISPLAY 'Releasing memory resources...'
    DISPLAY 'Closing log files...'
    DISPLAY 'Cleanup completed'
    GOBACK.
 
END PROGRAM CLEANUP-RESOURCES.
 
END PROGRAM ADVANCED-GOBACK-DEMO.

Best Practices

Knowledge Check

Test Your Understanding

Question 1: Basic Usage

What does GOBACK do in a subprogram?

Answer: GOBACK returns control from the subprogram to the calling program, terminating the current subprogram's execution.

Question 2: Main Program Usage

What happens when GOBACK is used in a main program?

Answer: In a main program, GOBACK terminates the entire program execution, similar to STOP RUN but with more modern semantics.

Question 3: Advantages

Why is GOBACK preferred over EXIT PROGRAM?

Answer: GOBACK is more versatile (works in both main and subprograms), follows modern COBOL standards, and provides more consistent behavior across different program contexts.

Common Patterns

Error Handling Pattern
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PROCEDURE DIVISION USING INPUT-DATA RESULT-CODE.
    MOVE 0 TO RESULT-CODE
    
    *> Validation
    IF INPUT-DATA = SPACES
        MOVE 001 TO RESULT-CODE
        GOBACK
    END-IF
    
    *> Processing
    PERFORM BUSINESS-LOGIC
    
    *> Success
    GOBACK.
Resource Management
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PROCEDURE DIVISION.
    PERFORM INITIALIZE-RESOURCES
    
    IF INITIALIZATION-FAILED
        PERFORM CLEANUP-RESOURCES
        GOBACK
    END-IF
    
    PERFORM MAIN-PROCESSING
    PERFORM CLEANUP-RESOURCES
    GOBACK.

Frequently Asked Questions

Related Concepts

Program Control

Program flow control and termination techniques

Subprogram Communication

Inter-program communication and parameter passing

Return Mechanisms

Program return and control transfer methods