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COBOL Tutorial

COBOL BOTTOM Clause

The BOTTOM clause in COBOL is a powerful report formatting feature used to control page layout and positioning in printed reports and formatted output. This clause defines the bottom margin of a page and determines where footings, totals, and page endings should be placed in report generation. BOTTOM is essential for creating professional-looking reports, ensuring consistent page formatting, managing white space, controlling page breaks, and optimizing printed output layout in business applications, financial reports, inventory systems, and any scenario where precise page formatting and professional presentation of data are critical for business communication and documentation requirements.

Understanding BOTTOM Clause

The BOTTOM clause specifies the bottom margin of a report page by defining how many lines from the bottom of the page should be reserved. This ensures proper spacing for footings, page numbers, and maintains consistent formatting across multi-page reports. It's commonly used in conjunction with TOP and PAGE clauses for complete page layout control.

Key Applications:

  • Report page layout and formatting
  • Footer placement and positioning
  • Page break control and management
  • White space optimization
  • Professional document presentation
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ENVIRONMENT DIVISION.
CONFIGURATION SECTION.
SOURCE-COMPUTER. IBM-370.
OBJECT-COMPUTER. IBM-370.
 
INPUT-OUTPUT SECTION.
FILE-CONTROL.
    SELECT REPORT-FILE ASSIGN TO PRINTER.
 
DATA DIVISION.
FILE SECTION.
FD  REPORT-FILE
    LABEL RECORDS ARE OMITTED
    LINAGE IS 60 LINES
    WITH FOOTING AT 55
    LINES AT TOP 5
    LINES AT BOTTOM 3.
 
01  REPORT-RECORD        PIC X(132).
 
WORKING-STORAGE SECTION.
01  PAGE-CONTROL.
    05  CURRENT-PAGE      PIC 999 VALUE 1.
    05  LINE-COUNT        PIC 99 VALUE ZERO.
    05  MAX-LINES         PIC 99 VALUE 52.
    05  FOOTER-LINE       PIC 99 VALUE 55.
 
PROCEDURE DIVISION.
GENERATE-REPORT.
    OPEN OUTPUT REPORT-FILE
    PERFORM WRITE-REPORT-HEADER
    PERFORM PROCESS-DETAIL-LINES
    PERFORM WRITE-REPORT-FOOTER
    CLOSE REPORT-FILE.

Page Layout Control

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*> Comprehensive page layout with BOTTOM clause
DATA DIVISION.
WORKING-STORAGE SECTION.
01  PAGE-LAYOUT-CONTROL.
    05  PAGE-SIZE         PIC 99 VALUE 66.
    05  TOP-MARGIN        PIC 99 VALUE 6.
    05  BOTTOM-MARGIN     PIC 99 VALUE 6.
    05  USABLE-LINES      PIC 99 VALUE 54.
    05  FOOTER-START      PIC 99 VALUE 60.
 
01  REPORT-HEADERS.
    05  MAIN-TITLE        PIC X(80) VALUE 
        "                    MONTHLY SALES REPORT".
    05  SUB-TITLE         PIC X(80) VALUE 
        "                      REGIONAL SUMMARY".
    05  COLUMN-HEADERS    PIC X(80) VALUE 
        "REGION     SALES AMT    COMMISSION    NET PROFIT".
 
01  REPORT-FOOTERS.
    05  PAGE-FOOTER       PIC X(80) VALUE ALL "-".
    05  COMPANY-INFO      PIC X(80) VALUE 
        "                ABC Corporation - Confidential".
 
FILE SECTION.
FD  SALES-REPORT
    LABEL RECORDS ARE OMITTED
    LINAGE IS 66 LINES
    WITH FOOTING AT 60
    LINES AT TOP 6
    LINES AT BOTTOM 6.
 
01  SALES-REPORT-LINE    PIC X(132).
 
PROCEDURE DIVISION.
CREATE-FORMATTED-REPORT.
    OPEN OUTPUT SALES-REPORT
    
    PERFORM WRITE-PAGE-HEADER
    PERFORM VARYING WS-REGION-IDX FROM 1 BY 1
        UNTIL WS-REGION-IDX > WS-TOTAL-REGIONS
        
        PERFORM CHECK-PAGE-OVERFLOW
        PERFORM WRITE-REGION-DETAILS
        ADD 1 TO LINE-COUNT
    END-PERFORM
    
    PERFORM WRITE-REPORT-TOTALS
    PERFORM WRITE-PAGE-FOOTER
    CLOSE SALES-REPORT.
 
CHECK-PAGE-OVERFLOW.
    IF LINE-COUNT >= USABLE-LINES
        PERFORM WRITE-PAGE-FOOTER
        PERFORM START-NEW-PAGE
        PERFORM WRITE-PAGE-HEADER
    END-IF.
 
WRITE-PAGE-HEADER.
    WRITE SALES-REPORT-LINE FROM MAIN-TITLE
        AFTER ADVANCING PAGE
    WRITE SALES-REPORT-LINE FROM SUB-TITLE
        AFTER ADVANCING 2 LINES
    WRITE SALES-REPORT-LINE FROM COLUMN-HEADERS
        AFTER ADVANCING 3 LINES
    MOVE 6 TO LINE-COUNT.
 
WRITE-PAGE-FOOTER.
    WRITE SALES-REPORT-LINE FROM PAGE-FOOTER
        AFTER ADVANCING TO FOOTING
    STRING "Page " CURRENT-PAGE " of Report"
        DELIMITED BY SIZE INTO WS-PAGE-NUMBER-LINE
    END-STRING
    WRITE SALES-REPORT-LINE FROM WS-PAGE-NUMBER-LINE
        AFTER ADVANCING 1 LINE
    WRITE SALES-REPORT-LINE FROM COMPANY-INFO
        AFTER ADVANCING 1 LINE.

Advanced Report Formatting

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*> Multi-column report with precise bottom control
DATA DIVISION.
WORKING-STORAGE SECTION.
01  ADVANCED-PAGE-CONTROL.
    05  PHYSICAL-PAGE-SIZE    PIC 999 VALUE 132.
    05  LOGICAL-PAGE-SIZE     PIC 99 VALUE 60.
    05  HEADER-LINES          PIC 99 VALUE 8.
    05  FOOTER-LINES          PIC 99 VALUE 5.
    05  DETAIL-LINES          PIC 99 VALUE 47.
    05  CURRENT-LINE          PIC 99 VALUE ZERO.
 
01  MULTI-COLUMN-LAYOUT.
    05  COLUMN-1-START        PIC 99 VALUE 1.
    05  COLUMN-2-START        PIC 99 VALUE 45.
    05  COLUMN-3-START        PIC 99 VALUE 89.
    05  COLUMN-WIDTH          PIC 99 VALUE 40.
 
01  REPORT-SPACING.
    05  SINGLE-SPACE          PIC 9 VALUE 1.
    05  DOUBLE-SPACE          PIC 9 VALUE 2.
    05  TRIPLE-SPACE          PIC 9 VALUE 3.
 
01  FOOTER-ELEMENTS.
    05  SEPARATOR-LINE        PIC X(132) VALUE ALL "=".
    05  TOTAL-LINE            PIC X(132).
    05  GRAND-TOTAL-LINE      PIC X(132).
    05  DATE-TIME-LINE        PIC X(132).
    05  CONFIDENTIAL-LINE     PIC X(132) VALUE 
        "           CONFIDENTIAL - INTERNAL USE ONLY".
 
FILE SECTION.
FD  MULTI-COLUMN-REPORT
    LABEL RECORDS ARE OMITTED
    LINAGE IS 60 LINES
    WITH FOOTING AT 55
    LINES AT TOP 8
    LINES AT BOTTOM 5.
 
01  MULTI-REPORT-LINE       PIC X(132).
 
PROCEDURE DIVISION.
GENERATE-MULTI-COLUMN-REPORT.
    PERFORM INITIALIZE-REPORT-PROCESSING
    PERFORM PRINT-REPORT-HEADER
    
    PERFORM VARYING WS-PAGE-NUM FROM 1 BY 1
        UNTIL END-OF-DATA
        
        PERFORM PROCESS-PAGE-DETAILS
        PERFORM CHECK-FOOTER-REQUIREMENTS
        
        IF NOT END-OF-DATA
            PERFORM ADVANCE-TO-NEXT-PAGE
        END-IF
    END-PERFORM
    
    PERFORM FINALIZE-REPORT-PROCESSING.
 
PROCESS-PAGE-DETAILS.
    PERFORM VARYING CURRENT-LINE FROM 1 BY 1
        UNTIL CURRENT-LINE > DETAIL-LINES 
           OR END-OF-DATA
           
        PERFORM FORMAT-DETAIL-LINE
        PERFORM WRITE-DETAIL-WITH-SPACING
        
        IF CURRENT-LINE = DETAIL-LINES
            PERFORM PREPARE-PAGE-FOOTER
        END-IF
    END-PERFORM.
 
CHECK-FOOTER-REQUIREMENTS.
    *> Calculate space needed for footers
    COMPUTE WS-SPACE-REMAINING = 
        FOOTER-LINES - (LOGICAL-PAGE-SIZE - CURRENT-LINE)
    
    IF WS-SPACE-REMAINING <= 0
        PERFORM WRITE-STANDARD-FOOTER
    ELSE
        PERFORM WRITE-COMPRESSED-FOOTER
    END-IF.
 
WRITE-STANDARD-FOOTER.
    WRITE MULTI-REPORT-LINE FROM SEPARATOR-LINE
        AFTER ADVANCING TO FOOTING
    
    *> Format and write totals
    PERFORM FORMAT-PAGE-TOTALS
    WRITE MULTI-REPORT-LINE FROM TOTAL-LINE
        AFTER ADVANCING SINGLE-SPACE
    
    *> Add timestamp
    PERFORM GET-CURRENT-DATE-TIME
    WRITE MULTI-REPORT-LINE FROM DATE-TIME-LINE
        AFTER ADVANCING SINGLE-SPACE
    
    WRITE MULTI-REPORT-LINE FROM CONFIDENTIAL-LINE
        AFTER ADVANCING DOUBLE-SPACE.
 
FORMAT-PAGE-TOTALS.
    STRING "Page Total: $" WS-PAGE-TOTAL 
           "    Running Total: $" WS-RUNNING-TOTAL
           "    Page " WS-CURRENT-PAGE
        DELIMITED BY SIZE INTO TOTAL-LINE
    END-STRING.

Dynamic Page Management

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*> Dynamic page management with variable content
DATA DIVISION.
WORKING-STORAGE SECTION.
01  DYNAMIC-PAGE-CONTROL.
    05  VARIABLE-CONTENT-FLAG   PIC X VALUE 'N'.
        88  VARIABLE-CONTENT    VALUE 'Y'.
    05  MINIMUM-FOOTER-SPACE    PIC 99 VALUE 10.
    05  PREFERRED-FOOTER-SPACE  PIC 99 VALUE 15.
    05  EMERGENCY-BREAK-LINE    PIC 99 VALUE 50.
 
01  CONTENT-ANALYSIS.
    05  DETAIL-COMPLEXITY       PIC 9 VALUE 1.
        88  SIMPLE-DETAILS      VALUE 1.
        88  COMPLEX-DETAILS     VALUE 2.
        88  VERY-COMPLEX-DETAILS VALUE 3.
    05  FOOTER-REQUIREMENTS     PIC 99 VALUE 5.
    05  SPECIAL-NOTES-COUNT     PIC 99 VALUE ZERO.
 
01  PAGE-OPTIMIZATION.
    05  OPTIMAL-BREAK-POINT     PIC 99.
    05  CONTENT-DENSITY         PIC 99V99 COMP-3.
    05  READABILITY-FACTOR      PIC 99V99 COMP-3.
 
PROCEDURE DIVISION.
OPTIMIZE-PAGE-LAYOUT.
    PERFORM ANALYZE-CONTENT-REQUIREMENTS
    PERFORM CALCULATE-OPTIMAL-LAYOUT
    PERFORM GENERATE-OPTIMIZED-PAGES.
 
ANALYZE-CONTENT-REQUIREMENTS.
    *> Determine content complexity
    EVALUATE TRUE
        WHEN WS-DETAIL-FIELD-COUNT < 5
            SET SIMPLE-DETAILS TO TRUE
            MOVE 5 TO FOOTER-REQUIREMENTS
        WHEN WS-DETAIL-FIELD-COUNT < 10
            SET COMPLEX-DETAILS TO TRUE
            MOVE 8 TO FOOTER-REQUIREMENTS
        WHEN OTHER
            SET VERY-COMPLEX-DETAILS TO TRUE
            MOVE 12 TO FOOTER-REQUIREMENTS
    END-EVALUATE
    
    *> Check for special requirements
    IF WS-FOOTNOTE-COUNT > 0
        ADD WS-FOOTNOTE-COUNT TO FOOTER-REQUIREMENTS
    END-IF
    
    IF WS-LEGAL-DISCLAIMERS > 0
        ADD 3 TO FOOTER-REQUIREMENTS
    END-IF.
 
CALCULATE-OPTIMAL-LAYOUT.
    *> Calculate best break point
    COMPUTE OPTIMAL-BREAK-POINT = 
        LOGICAL-PAGE-SIZE - FOOTER-REQUIREMENTS - 2
    
    *> Ensure minimum readability
    IF OPTIMAL-BREAK-POINT < EMERGENCY-BREAK-LINE
        MOVE EMERGENCY-BREAK-LINE TO OPTIMAL-BREAK-POINT
        PERFORM COMPRESS-FOOTER-CONTENT
    END-IF
    
    *> Calculate content density
    COMPUTE CONTENT-DENSITY = 
        (OPTIMAL-BREAK-POINT - HEADER-LINES) / LOGICAL-PAGE-SIZE.
 
GENERATE-OPTIMIZED-PAGES.
    PERFORM UNTIL END-OF-INPUT-DATA
        PERFORM RESET-PAGE-COUNTERS
        PERFORM WRITE-ADAPTIVE-HEADER
        
        PERFORM VARYING CURRENT-LINE FROM 1 BY 1
            UNTIL CURRENT-LINE >= OPTIMAL-BREAK-POINT
               OR END-OF-INPUT-DATA
               OR SPECIAL-BREAK-REQUIRED
            
            PERFORM PROCESS-DETAIL-LINE
            PERFORM CHECK-SPECIAL-CONDITIONS
        END-PERFORM
        
        PERFORM WRITE-ADAPTIVE-FOOTER
        
        IF NOT END-OF-INPUT-DATA
            PERFORM ADVANCE-TO-NEW-PAGE
        END-IF
    END-PERFORM.
 
CHECK-SPECIAL-CONDITIONS.
    *> Check if we need special page break
    IF WS-RECORD-TYPE = "SECTION-BREAK"
        SET SPECIAL-BREAK-REQUIRED TO TRUE
        PERFORM WRITE-SECTION-FOOTER
    END-IF
    
    *> Check for table overflow
    IF WS-TABLE-ROW-COUNT > WS-MAX-TABLE-ROWS
        SET SPECIAL-BREAK-REQUIRED TO TRUE
        PERFORM WRITE-TABLE-CONTINUATION-NOTE
    END-IF.
 
WRITE-ADAPTIVE-FOOTER.
    *> Calculate available footer space
    COMPUTE WS-AVAILABLE-SPACE = 
        LOGICAL-PAGE-SIZE - CURRENT-LINE - HEADER-LINES
    
    EVALUATE TRUE
        WHEN WS-AVAILABLE-SPACE >= PREFERRED-FOOTER-SPACE
            PERFORM WRITE-FULL-FOOTER
        WHEN WS-AVAILABLE-SPACE >= MINIMUM-FOOTER-SPACE
            PERFORM WRITE-STANDARD-FOOTER
        WHEN OTHER
            PERFORM WRITE-MINIMAL-FOOTER
    END-EVALUATE.

Best Practices

BOTTOM Clause Guidelines:

  • Reserve adequate space for footers and page numbers
  • Consider printer margins and paper size constraints
  • Use consistent spacing throughout the report
  • Plan for variable content length and overflow
  • Test page layout with different data volumes
  • Implement proper page break logic
  • Include error handling for page overflow
  • Optimize for both screen and print display

Common Use Cases

Financial Reports

Use BOTTOM for consistent footer placement in financial statements, balance sheets, and accounting reports with totals and signatures.

Inventory Lists

Control page breaks in inventory reports to ensure product categories don't split across pages inappropriately.

Legal Documents

Maintain proper footer spacing for legal disclaimers, signatures, and regulatory compliance information.

Customer Statements

Ensure consistent layout in customer billing statements with proper space for payment instructions and contact info.

FAQ

Q: How does BOTTOM interact with FOOTING?

BOTTOM defines the bottom margin, while FOOTING specifies the line number where footings should begin. FOOTING must be within the BOTTOM margin area.

Q: Can BOTTOM be changed dynamically?

BOTTOM is typically defined at file definition time and remains constant. For dynamic control, use programmatic line counting and conditional logic.

Q: What happens if content exceeds the BOTTOM margin?

Content that exceeds the BOTTOM margin may cause automatic page breaks or print into the margin area, depending on the system configuration.