MainframeMaster

COBOL DISPLAY-1 Format

Master the DISPLAY-1 numeric format for character-based representation of signed numeric data with separate sign storage in COBOL applications.

Overview

DISPLAY-1 is a specialized numeric data format in COBOL that stores signed numeric values as character strings with the sign stored in a separate character position. This format provides excellent readability and portability, making it ideal for data interchange between different systems and for applications where human-readable numeric data is required.

Unlike the standard DISPLAY format, which embeds the sign information in the zone bits of the last digit, DISPLAY-1 uses a dedicated character position for the sign. This approach eliminates potential compatibility issues between different systems and character sets, making DISPLAY-1 data truly portable across various platforms.

DISPLAY-1 format is particularly valuable in mainframe environments where data exchange with external systems is common, and in applications that require clear, unambiguous representation of signed numeric values. Understanding DISPLAY-1 is essential for developing robust COBOL applications that handle numeric data efficiently and reliably.

Basic Syntax and Declaration

DISPLAY-1 format is specified using the USAGE clause in data declarations:

cobol
1
2
3
4
5
6
DATA DIVISION.
WORKING-STORAGE SECTION.
01 WS-NUMERIC-FIELDS.
    05 WS-AMOUNT        PIC S9(7)V99 USAGE DISPLAY-1.
    05 WS-QUANTITY      PIC S9(5) USAGE DISPLAY-1.
    05 WS-PERCENTAGE    PIC S9(3)V99 USAGE DISPLAY-1.

The 'S' in the PICTURE clause indicates that the field is signed, and USAGE DISPLAY-1 specifies the storage format with separate sign representation.

Sign Position Control

You can control the position of the sign character using the SIGN clause:

cobol
1
2
3
4
5
01 WS-SIGNED-FIELDS.
    05 WS-LEADING-SIGN  PIC S9(5) USAGE DISPLAY-1
                        SIGN IS LEADING SEPARATE.
    05 WS-TRAILING-SIGN PIC S9(5) USAGE DISPLAY-1
                        SIGN IS TRAILING SEPARATE.

LEADING SEPARATE places the sign before the digits, while TRAILING SEPARATE places it after the digits.

Storage and Memory Layout

Memory Allocation

DISPLAY-1 format requires specific memory allocation based on the field definition:

cobol
1
2
3
4
5
6
7
8
9
01 WS-STORAGE-EXAMPLES.
    * 5 digits + 1 sign = 6 bytes total
    05 WS-FIELD-1       PIC S9(5) USAGE DISPLAY-1.
    
    * 7 digits + 2 decimal + 1 sign = 10 bytes total
    05 WS-FIELD-2       PIC S9(7)V99 USAGE DISPLAY-1.
    
    * 3 digits + 1 sign = 4 bytes total
    05 WS-FIELD-3       PIC S999 USAGE DISPLAY-1.

Each digit requires one byte, and the sign requires an additional byte, regardless of its position.

Character Representation

Understanding how values are stored in DISPLAY-1 format:

cobol
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
WORKING-STORAGE SECTION.
01 WS-DEMO-VALUES.
    05 WS-POSITIVE      PIC S9(3) USAGE DISPLAY-1 VALUE +123.
    05 WS-NEGATIVE      PIC S9(3) USAGE DISPLAY-1 VALUE -456.
    05 WS-ZERO          PIC S9(3) USAGE DISPLAY-1 VALUE ZERO.
 
PROCEDURE DIVISION.
DISPLAY-STORAGE-FORMAT.
    * WS-POSITIVE stored as "+123" (4 bytes)
    * WS-NEGATIVE stored as "-456" (4 bytes)  
    * WS-ZERO stored as "+000" (4 bytes)
    
    DISPLAY "Positive: " WS-POSITIVE
    DISPLAY "Negative: " WS-NEGATIVE
    DISPLAY "Zero: " WS-ZERO.

The sign character is explicitly visible and takes up a separate storage position.

Arithmetic Operations

Basic Calculations

DISPLAY-1 fields can be used directly in arithmetic operations:

cobol
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
WORKING-STORAGE SECTION.
01 WS-CALC-FIELDS.
    05 WS-NUM1          PIC S9(5)V99 USAGE DISPLAY-1.
    05 WS-NUM2          PIC S9(5)V99 USAGE DISPLAY-1.
    05 WS-RESULT        PIC S9(7)V99 USAGE DISPLAY-1.
 
PROCEDURE DIVISION.
PERFORM-CALCULATIONS.
    MOVE 1234.56 TO WS-NUM1
    MOVE -567.89 TO WS-NUM2
    
    ADD WS-NUM1 TO WS-NUM2 GIVING WS-RESULT
    DISPLAY "Addition: " WS-RESULT
    
    MULTIPLY WS-NUM1 BY WS-NUM2 GIVING WS-RESULT
    DISPLAY "Multiplication: " WS-RESULT.

COBOL automatically handles the conversion between DISPLAY-1 format and internal arithmetic representation.

Mixed Format Operations

DISPLAY-1 fields can be used with other numeric formats:

cobol
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
WORKING-STORAGE SECTION.
01 WS-MIXED-FORMATS.
    05 WS-DISPLAY1      PIC S9(5)V99 USAGE DISPLAY-1.
    05 WS-COMP3         PIC S9(5)V99 USAGE COMP-3.
    05 WS-BINARY        PIC S9(5)V99 USAGE BINARY.
    05 WS-RESULT        PIC S9(7)V99 USAGE DISPLAY-1.
 
PROCEDURE DIVISION.
MIXED-ARITHMETIC.
    MOVE 1000.50 TO WS-DISPLAY1
    MOVE 2000.75 TO WS-COMP3
    MOVE 500.25 TO WS-BINARY
    
    COMPUTE WS-RESULT = WS-DISPLAY1 + WS-COMP3 - WS-BINARY
    DISPLAY "Mixed calculation result: " WS-RESULT.

COBOL handles automatic conversion between different numeric formats during arithmetic operations.

Data Validation and Editing

Numeric Validation

Implementing validation for DISPLAY-1 numeric data:

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
WORKING-STORAGE SECTION.
01 WS-INPUT-FIELD       PIC X(10).
01 WS-NUMERIC-FIELD     PIC S9(7)V99 USAGE DISPLAY-1.
01 WS-VALIDATION-FLAGS.
    05 WS-IS-NUMERIC    PIC X(1).
    05 WS-IS-VALID      PIC X(1).
 
PROCEDURE DIVISION.
VALIDATE-INPUT.
    ACCEPT WS-INPUT-FIELD
    
    IF WS-INPUT-FIELD IS NUMERIC
        MOVE "Y" TO WS-IS-NUMERIC
        MOVE WS-INPUT-FIELD TO WS-NUMERIC-FIELD
        PERFORM RANGE-CHECK
    ELSE
        MOVE "N" TO WS-IS-NUMERIC
        DISPLAY "Invalid numeric input"
    END-IF.
 
RANGE-CHECK.
    IF WS-NUMERIC-FIELD >= -9999999.99 AND
       WS-NUMERIC-FIELD <= 9999999.99
        MOVE "Y" TO WS-IS-VALID
        DISPLAY "Valid number: " WS-NUMERIC-FIELD
    ELSE
        MOVE "N" TO WS-IS-VALID
        DISPLAY "Number out of range"
    END-IF.

Proper validation ensures data integrity when working with DISPLAY-1 fields.

Output Formatting

Formatting DISPLAY-1 data for output presentation:

cobol
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
WORKING-STORAGE SECTION.
01 WS-SOURCE-AMOUNT     PIC S9(7)V99 USAGE DISPLAY-1.
01 WS-FORMATTED-OUTPUT.
    05 WS-SIGN-CHAR     PIC X(1).
    05 WS-DOLLAR-SIGN   PIC X(1) VALUE "$".
    05 WS-AMOUNT-EDIT   PIC ZZ,ZZZ,ZZ9.99.
 
PROCEDURE DIVISION.
FORMAT-FOR-DISPLAY.
    MOVE 1234567.89 TO WS-SOURCE-AMOUNT
    
    IF WS-SOURCE-AMOUNT < ZERO
        MOVE "-" TO WS-SIGN-CHAR
        COMPUTE WS-SOURCE-AMOUNT = WS-SOURCE-AMOUNT * -1
    ELSE
        MOVE "+" TO WS-SIGN-CHAR
    END-IF
    
    MOVE WS-SOURCE-AMOUNT TO WS-AMOUNT-EDIT
    
    DISPLAY WS-SIGN-CHAR WS-DOLLAR-SIGN WS-AMOUNT-EDIT.

This formatting approach provides professional output presentation while preserving the original DISPLAY-1 data.

File I/O and Data Exchange

File Processing

Using DISPLAY-1 fields in file processing operations:

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
DATA DIVISION.
FILE SECTION.
FD TRANSACTION-FILE.
01 TRANSACTION-RECORD.
    05 TRANS-ID         PIC X(10).
    05 TRANS-AMOUNT     PIC S9(9)V99 USAGE DISPLAY-1.
    05 TRANS-DATE       PIC X(8).
    05 TRANS-TYPE       PIC X(1).
 
WORKING-STORAGE SECTION.
01 WS-TOTAL-AMOUNT      PIC S9(11)V99 USAGE DISPLAY-1.
01 WS-RECORD-COUNT      PIC 9(6) VALUE ZERO.
 
PROCEDURE DIVISION.
PROCESS-TRANSACTIONS.
    OPEN INPUT TRANSACTION-FILE
    
    PERFORM UNTIL WS-EOF = "Y"
        READ TRANSACTION-FILE
            AT END
                MOVE "Y" TO WS-EOF
            NOT AT END
                ADD 1 TO WS-RECORD-COUNT
                ADD TRANS-AMOUNT TO WS-TOTAL-AMOUNT
                PERFORM VALIDATE-TRANSACTION
        END-READ
    END-PERFORM
    
    CLOSE TRANSACTION-FILE
    DISPLAY "Total records: " WS-RECORD-COUNT
    DISPLAY "Total amount: " WS-TOTAL-AMOUNT.

DISPLAY-1 format ensures consistent numeric representation across different file processing operations.

Data Export and Import

Handling DISPLAY-1 data in export/import scenarios:

cobol
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
WORKING-STORAGE SECTION.
01 WS-EXPORT-RECORD.
    05 WS-FIELD1        PIC S9(7)V99 USAGE DISPLAY-1.
    05 WS-FIELD2        PIC S9(5) USAGE DISPLAY-1.
    05 WS-FIELD3        PIC S9(3)V999 USAGE DISPLAY-1.
 
01 WS-CSV-OUTPUT        PIC X(100).
 
PROCEDURE DIVISION.
EXPORT-TO-CSV.
    MOVE 12345.67 TO WS-FIELD1
    MOVE -999 TO WS-FIELD2
    MOVE 123.456 TO WS-FIELD3
    
    STRING WS-FIELD1 DELIMITED BY SIZE
           "," DELIMITED BY SIZE
           WS-FIELD2 DELIMITED BY SIZE
           "," DELIMITED BY SIZE
           WS-FIELD3 DELIMITED BY SIZE
           INTO WS-CSV-OUTPUT
    
    DISPLAY "CSV Output: " WS-CSV-OUTPUT.

DISPLAY-1 format provides excellent compatibility for data exchange with external systems.

Performance Considerations

Storage Efficiency

Comparing storage requirements across different numeric formats:

cobol
1
2
3
4
5
6
7
8
9
10
* Storage comparison for PIC S9(7)V99:
01 WS-STORAGE-COMPARISON.
    * DISPLAY-1: 10 bytes (7+2 digits + 1 sign)
    05 WS-DISPLAY1      PIC S9(7)V99 USAGE DISPLAY-1.
    
    * COMP-3: 5 bytes (packed decimal)
    05 WS-COMP3         PIC S9(7)V99 USAGE COMP-3.
    
    * BINARY: 8 bytes (binary representation)
    05 WS-BINARY        PIC S9(7)V99 USAGE BINARY.

DISPLAY-1 uses more storage than packed formats but provides superior readability and portability.

Processing Speed

Optimizing performance when using DISPLAY-1 fields:

cobol
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
WORKING-STORAGE SECTION.
01 WS-PERFORMANCE-TEST.
    05 WS-LOOP-COUNTER  PIC 9(6) VALUE ZERO.
    05 WS-START-TIME    PIC 9(8).
    05 WS-END-TIME      PIC 9(8).
    05 WS-DISPLAY1-SUM  PIC S9(9)V99 USAGE DISPLAY-1.
 
PROCEDURE DIVISION.
PERFORMANCE-TEST.
    ACCEPT WS-START-TIME FROM TIME
    
    PERFORM VARYING WS-LOOP-COUNTER FROM 1 BY 1
        UNTIL WS-LOOP-COUNTER > 100000
        ADD 1.23 TO WS-DISPLAY1-SUM
    END-PERFORM
    
    ACCEPT WS-END-TIME FROM TIME
    COMPUTE WS-ELAPSED = WS-END-TIME - WS-START-TIME
    DISPLAY "Processing time: " WS-ELAPSED " centiseconds".

While DISPLAY-1 may be slower than binary formats, the performance difference is often negligible for most applications.

Best Practices and Guidelines

When to Use DISPLAY-1

Choose DISPLAY-1 format in these scenarios:

  • Data exchange with external systems requiring character-based numeric data
  • Applications where human readability of numeric data is important
  • Cross-platform data compatibility requirements
  • Debugging and testing scenarios where data inspection is needed
  • Legacy system integration where DISPLAY-1 format is established
  • Report generation with embedded numeric values

Implementation Guidelines

Follow these guidelines for effective DISPLAY-1 usage:

cobol
1
2
3
4
5
6
7
8
9
10
11
12
13
14
* Good practice: Consistent sign positioning
01 WS-FINANCIAL-DATA.
    05 WS-AMOUNT        PIC S9(9)V99 USAGE DISPLAY-1
                        SIGN IS LEADING SEPARATE.
    05 WS-BALANCE       PIC S9(9)V99 USAGE DISPLAY-1
                        SIGN IS LEADING SEPARATE.
    05 WS-INTEREST      PIC S9(7)V99 USAGE DISPLAY-1
                        SIGN IS LEADING SEPARATE.
 
* Good practice: Appropriate field sizing
01 WS-COUNTERS.
    05 WS-SMALL-COUNT   PIC S9(3) USAGE DISPLAY-1.
    05 WS-MEDIUM-COUNT  PIC S9(5) USAGE DISPLAY-1.
    05 WS-LARGE-COUNT   PIC S9(9) USAGE DISPLAY-1.

Consistent formatting and appropriate field sizing improve code maintainability and data integrity.

Hands-on Exercise

Exercise: Financial Calculator with DISPLAY-1

Create a COBOL program that implements a financial calculator using DISPLAY-1 format for all numeric operations.

Requirements:

  • Use DISPLAY-1 format for all monetary amounts
  • Implement basic arithmetic operations (add, subtract, multiply, divide)
  • Include input validation and error handling
  • Format output for professional presentation
  • Handle both positive and negative amounts
View Solution
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
IDENTIFICATION DIVISION.
PROGRAM-ID. FINANCIAL-CALC.
 
DATA DIVISION.
WORKING-STORAGE SECTION.
01 WS-CALCULATOR-DATA.
    05 WS-AMOUNT1       PIC S9(9)V99 USAGE DISPLAY-1
                        SIGN IS LEADING SEPARATE.
    05 WS-AMOUNT2       PIC S9(9)V99 USAGE DISPLAY-1
                        SIGN IS LEADING SEPARATE.
    05 WS-RESULT        PIC S9(11)V99 USAGE DISPLAY-1
                        SIGN IS LEADING SEPARATE.
    05 WS-OPERATION     PIC X(1).
 
01 WS-INPUT-FIELDS.
    05 WS-INPUT1        PIC X(15).
    05 WS-INPUT2        PIC X(15).
 
01 WS-FORMATTED-OUTPUT.
    05 WS-RESULT-EDIT   PIC +Z,ZZZ,ZZZ,ZZ9.99.
 
PROCEDURE DIVISION.
MAIN-LOGIC.
    PERFORM GET-INPUTS
    PERFORM VALIDATE-INPUTS
    PERFORM CALCULATE-RESULT
    PERFORM DISPLAY-RESULT
    GOBACK.
 
GET-INPUTS.
    DISPLAY "Enter first amount: " WITH NO ADVANCING
    ACCEPT WS-INPUT1
    DISPLAY "Enter operation (+, -, *, /): " WITH NO ADVANCING
    ACCEPT WS-OPERATION
    DISPLAY "Enter second amount: " WITH NO ADVANCING
    ACCEPT WS-INPUT2.
 
VALIDATE-INPUTS.
    IF WS-INPUT1 IS NUMERIC
        MOVE WS-INPUT1 TO WS-AMOUNT1
    ELSE
        DISPLAY "Invalid first amount"
        GOBACK
    END-IF
    
    IF WS-INPUT2 IS NUMERIC
        MOVE WS-INPUT2 TO WS-AMOUNT2
    ELSE
        DISPLAY "Invalid second amount"
        GOBACK
    END-IF.
 
CALCULATE-RESULT.
    EVALUATE WS-OPERATION
        WHEN "+"
            ADD WS-AMOUNT1 TO WS-AMOUNT2 GIVING WS-RESULT
        WHEN "-"
            SUBTRACT WS-AMOUNT2 FROM WS-AMOUNT1 GIVING WS-RESULT
        WHEN "*"
            MULTIPLY WS-AMOUNT1 BY WS-AMOUNT2 GIVING WS-RESULT
        WHEN "/"
            IF WS-AMOUNT2 NOT = ZERO
                DIVIDE WS-AMOUNT1 BY WS-AMOUNT2 GIVING WS-RESULT
            ELSE
                DISPLAY "Division by zero error"
                GOBACK
            END-IF
        WHEN OTHER
            DISPLAY "Invalid operation"
            GOBACK
    END-EVALUATE.
 
DISPLAY-RESULT.
    MOVE WS-RESULT TO WS-RESULT-EDIT
    DISPLAY "Result: " WS-RESULT-EDIT.

Quiz

Test Your Knowledge

1. How is the sign stored in DISPLAY-1 format?

2. What is the storage requirement for PIC S9(5) USAGE DISPLAY-1?

3. What is the main advantage of DISPLAY-1 over regular DISPLAY format?

View Answers

1. In a separate character position - DISPLAY-1 stores the sign in a dedicated character position, separate from the numeric digits.

2. 6 bytes - 5 bytes for the digits plus 1 byte for the separate sign character.

3. Better portability and readability - DISPLAY-1 provides superior cross-platform compatibility and human readability compared to regular DISPLAY format.

Frequently Asked Questions

Related Concepts

Data Types and Formats

Understanding different COBOL data types and their storage formats

Numeric Data Handling

Working with various numeric formats and representations in COBOL

USAGE Clause Variations

Exploring different USAGE clause options for data storage optimization

Sign Handling

Managing positive and negative numbers in COBOL applications