MainframeMaster

COBOL Data Sections

Data sections organize different types of data within the Data Division of COBOL programs. Learn Working Storage Section, File Section, Linkage Section, Local Storage Section, and Screen Section for effective data organization.

Working Storage Section

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       WORKING-STORAGE SECTION.
       01 WORKING-STORAGE-EXAMPLES.
           05 PROGRAM-CONSTANTS.
               10 C-MAX-RECORDS PIC 9(4) VALUE 1000.
               10 C-COMPANY-NAME PIC X(20) VALUE 'ACME CORPORATION'.
               10 C-DEFAULT-STATUS PIC X VALUE 'A'.
           05 PROGRAM-VARIABLES.
               10 WS-RECORD-COUNT PIC 9(6) VALUE 0.
               10 WS-TOTAL-AMOUNT PIC 9(9)V99 VALUE 0.
               10 WS-PROCESSING-FLAG PIC X VALUE 'N'.
                   88 WS-PROCESSING-COMPLETE VALUE 'Y'.
           05 WORK-AREAS.
               10 TEMP-BUFFER PIC X(100).
               10 CALCULATION-AREA PIC 9(9)V99.
               10 ERROR-MESSAGE PIC X(50).
       
       PROCEDURE DIVISION.
       PERFORM DEMONSTRATE-WORKING-STORAGE
       
       DEMONSTRATE-WORKING-STORAGE.
           DISPLAY 'Working Storage Section demonstration:'
           DISPLAY 'Max Records: ' C-MAX-RECORDS
           DISPLAY 'Company Name: ' C-COMPANY-NAME
           DISPLAY 'Default Status: ' C-DEFAULT-STATUS
           DISPLAY 'Record Count: ' WS-RECORD-COUNT
           DISPLAY 'Total Amount: ' WS-TOTAL-AMOUNT
           DISPLAY 'Processing Flag: ' WS-PROCESSING-FLAG.

The Working Storage Section contains program variables, constants, and work areas that persist throughout program execution. Data is initialized when the program starts and retains values between procedure calls.

File Section

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       FILE SECTION.
       FD CUSTOMER-MASTER-FILE
           LABEL RECORDS ARE STANDARD
           RECORDING MODE IS F
           BLOCK CONTAINS 0 RECORDS.
       01 CUSTOMER-MASTER-RECORD.
           05 CUSTOMER-ID PIC 9(6).
           05 CUSTOMER-NAME PIC X(30).
           05 CUSTOMER-ADDRESS PIC X(50).
           05 CUSTOMER-PHONE PIC X(12).
           05 CUSTOMER-BALANCE PIC 9(9)V99.
       
       FD TRANSACTION-FILE
           LABEL RECORDS ARE STANDARD
           RECORDING MODE IS F
           BLOCK CONTAINS 0 RECORDS.
       01 TRANSACTION-RECORD.
           05 TRANSACTION-ID PIC 9(8).
           05 TRANSACTION-DATE PIC 9(8).
           05 TRANSACTION-AMOUNT PIC 9(9)V99.
           05 TRANSACTION-DESCRIPTION PIC X(50).
       
       FD REPORT-FILE
           LABEL RECORDS ARE OMITTED
           RECORDING MODE IS F
           BLOCK CONTAINS 0 RECORDS.
       01 REPORT-LINE PIC X(132).
       
       PROCEDURE DIVISION.
       PERFORM DEMONSTRATE-FILE-SECTION
       
       DEMONSTRATE-FILE-SECTION.
           OPEN INPUT CUSTOMER-MASTER-FILE
           OPEN INPUT TRANSACTION-FILE
           OPEN OUTPUT REPORT-FILE
           
           DISPLAY 'File Section demonstration:'
           DISPLAY 'Customer Master File opened'
           DISPLAY 'Transaction File opened'
           DISPLAY 'Report File opened'
           
           CLOSE CUSTOMER-MASTER-FILE
           CLOSE TRANSACTION-FILE
           CLOSE REPORT-FILE.

The File Section defines file descriptions (FD) and record layouts for input/output files. Each FD describes file characteristics like record format, labels, and blocking, followed by record structure definitions.

Linkage Section

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       LINKAGE SECTION.
       01 LINKAGE-PARAMETERS.
           05 INPUT-PARAMETER-AREA.
               10 INPUT-PARAMETER-LENGTH PIC S9(4) COMP.
               10 INPUT-PARAMETER-DATA PIC X(100).
           05 OUTPUT-PARAMETER-AREA.
               10 OUTPUT-PARAMETER-RETURN-CODE PIC 9(4).
               10 OUTPUT-PARAMETER-MESSAGE PIC X(50).
           05 SHARED-DATA-AREA.
               10 SHARED-CUSTOMER-ID PIC 9(6).
               10 SHARED-CUSTOMER-NAME PIC X(30).
               10 SHARED-CUSTOMER-BALANCE PIC 9(9)V99.
       
       PROCEDURE DIVISION USING INPUT-PARAMETER-AREA
                                OUTPUT-PARAMETER-AREA
                                SHARED-DATA-AREA.
       PERFORM DEMONSTRATE-LINKAGE-SECTION
       
       DEMONSTRATE-LINKAGE-SECTION.
           DISPLAY 'Linkage Section demonstration:'
           DISPLAY 'Input Parameter Length: ' INPUT-PARAMETER-LENGTH
           DISPLAY 'Input Parameter Data: ' INPUT-PARAMETER-DATA
           DISPLAY 'Shared Customer ID: ' SHARED-CUSTOMER-ID
           DISPLAY 'Shared Customer Name: ' SHARED-CUSTOMER-NAME
           DISPLAY 'Shared Customer Balance: ' SHARED-CUSTOMER-BALANCE
           
           MOVE 0 TO OUTPUT-PARAMETER-RETURN-CODE
           MOVE 'PROCESSING COMPLETED' TO OUTPUT-PARAMETER-MESSAGE.

The Linkage Section defines parameters passed between programs and shared data areas. Data in this section is provided by the calling program and represents the interface between programs.

Local Storage Section

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       LOCAL-STORAGE SECTION.
       01 LOCAL-STORAGE-DATA.
           05 LOCAL-VARIABLES.
               10 LOCAL-COUNTER PIC 9(4) VALUE 0.
               10 LOCAL-TEMP-VALUE PIC 9(6)V99 VALUE 0.
               10 LOCAL-PROCESSING-FLAG PIC X VALUE 'N'.
           05 LOCAL-WORK-AREAS.
               10 LOCAL-BUFFER PIC X(200).
               10 LOCAL-CALCULATION PIC 9(9)V99.
               10 LOCAL-ERROR-CODE PIC 9(3).
       
       PROCEDURE DIVISION.
       PERFORM DEMONSTRATE-LOCAL-STORAGE
       
       DEMONSTRATE-LOCAL-STORAGE.
           DISPLAY 'Local Storage Section demonstration:'
           DISPLAY 'Local Counter: ' LOCAL-COUNTER
           DISPLAY 'Local Temp Value: ' LOCAL-TEMP-VALUE
           DISPLAY 'Local Processing Flag: ' LOCAL-PROCESSING-FLAG
           
           ADD 1 TO LOCAL-COUNTER
           MOVE 1500.50 TO LOCAL-TEMP-VALUE
           MOVE 'Y' TO LOCAL-PROCESSING-FLAG
           
           DISPLAY 'After modification:'
           DISPLAY 'Local Counter: ' LOCAL-COUNTER
           DISPLAY 'Local Temp Value: ' LOCAL-TEMP-VALUE
           DISPLAY 'Local Processing Flag: ' LOCAL-PROCESSING-FLAG.

The Local Storage Section provides automatic storage that is allocated when a program is called and deallocated when the program returns. Each call gets fresh storage, making it useful for recursive programs.

Screen Section

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       SCREEN SECTION.
       01 MAIN-SCREEN.
           05 BLANK SCREEN.
           05 LINE 1 COLUMN 1 VALUE 'CUSTOMER MANAGEMENT SYSTEM'.
           05 LINE 3 COLUMN 1 VALUE 'Customer ID:'.
           05 LINE 3 COLUMN 15 PIC 9(6) TO CUSTOMER-ID.
           05 LINE 4 COLUMN 1 VALUE 'Customer Name:'.
           05 LINE 4 COLUMN 15 PIC X(30) TO CUSTOMER-NAME.
           05 LINE 5 COLUMN 1 VALUE 'Account Balance:'.
           05 LINE 5 COLUMN 15 PIC 9(9)V99 TO CUSTOMER-BALANCE.
           05 LINE 7 COLUMN 1 VALUE 'Press ENTER to continue or ESC to exit'.
       
       01 CONFIRMATION-SCREEN.
           05 BLANK SCREEN.
           05 LINE 1 COLUMN 1 VALUE 'CONFIRMATION'.
           05 LINE 3 COLUMN 1 VALUE 'Customer ID: '.
           05 LINE 3 COLUMN 15 PIC 9(6) FROM CUSTOMER-ID.
           05 LINE 4 COLUMN 1 VALUE 'Customer Name: '.
           05 LINE 4 COLUMN 15 PIC X(30) FROM CUSTOMER-NAME.
           05 LINE 5 COLUMN 1 VALUE 'Account Balance: '.
           05 LINE 5 COLUMN 15 PIC 9(9)V99 FROM CUSTOMER-BALANCE.
       
       PROCEDURE DIVISION.
       PERFORM DEMONSTRATE-SCREEN-SECTION
       
       DEMONSTRATE-SCREEN-SECTION.
           DISPLAY 'Screen Section demonstration:'
           DISPLAY 'Main Screen defined'
           DISPLAY 'Confirmation Screen defined'
           DISPLAY 'Screen layouts ready for use'.

The Screen Section defines interactive screen layouts for terminal-based applications. It specifies screen positioning, field definitions, and user interaction elements for data entry and display.

Data Section Organization

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       IDENTIFICATION DIVISION.
       PROGRAM-ID. DATA-SECTIONS-DEMO.
       
       ENVIRONMENT DIVISION.
       INPUT-OUTPUT SECTION.
       FILE-CONTROL.
           SELECT CUSTOMER-FILE ASSIGN TO 'CUSTOMER.DAT'.
       
       DATA DIVISION.
       FILE SECTION.
       FD CUSTOMER-FILE
           LABEL RECORDS ARE STANDARD.
       01 CUSTOMER-RECORD PIC X(100).
       
       WORKING-STORAGE SECTION.
       01 PROGRAM-CONSTANTS.
           05 C-MAX-RECORDS PIC 9(4) VALUE 1000.
       01 PROGRAM-VARIABLES.
           05 WS-RECORD-COUNT PIC 9(6) VALUE 0.
       
       LINKAGE SECTION.
       01 LINKAGE-PARAMETERS.
           05 INPUT-DATA PIC X(50).
           05 OUTPUT-DATA PIC X(50).
       
       LOCAL-STORAGE SECTION.
       01 LOCAL-DATA.
           05 LOCAL-COUNTER PIC 9(4) VALUE 0.
       
       SCREEN SECTION.
       01 INPUT-SCREEN.
           05 LINE 1 COLUMN 1 VALUE 'Enter Data:'.
           05 LINE 1 COLUMN 15 PIC X(50) TO INPUT-DATA.
       
       PROCEDURE DIVISION USING LINKAGE-PARAMETERS.
       PERFORM DEMONSTRATE-SECTION-ORGANIZATION
       
       DEMONSTRATE-SECTION-ORGANIZATION.
           DISPLAY 'Data Section Organization:'
           DISPLAY 'File Section: File definitions'
           DISPLAY 'Working Storage: Program variables'
           DISPLAY 'Linkage Section: Parameters'
           DISPLAY 'Local Storage: Local variables'
           DISPLAY 'Screen Section: Screen layouts'.

Organize data sections in the proper order: File Section first, then Working Storage Section, followed by Linkage Section, Local Storage Section, and Screen Section. Each section serves specific purposes in program data organization.

Section Usage Guidelines

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       WORKING-STORAGE SECTION.
       01 SECTION-USAGE-GUIDELINES.
           05 CONSTANTS.
               10 C-MAX-RECORDS PIC 9(4) VALUE 1000.
               10 C-COMPANY-NAME PIC X(20) VALUE 'ACME CORP'.
           05 VARIABLES.
               10 WS-RECORD-COUNT PIC 9(6) VALUE 0.
               10 WS-TOTAL-AMOUNT PIC 9(9)V99 VALUE 0.
           05 WORK-AREAS.
               10 TEMP-BUFFER PIC X(100).
               10 CALCULATION-AREA PIC 9(9)V99.
       
       PROCEDURE DIVISION.
       PERFORM DEMONSTRATE-USAGE-GUIDELINES
       
       DEMONSTRATE-USAGE-GUIDELINES.
           DISPLAY 'Section Usage Guidelines:'
           DISPLAY 'Working Storage: Use for program variables and constants'
           DISPLAY 'File Section: Use for file and record definitions'
           DISPLAY 'Linkage Section: Use for program parameters'
           DISPLAY 'Local Storage: Use for recursive or reentrant programs'
           DISPLAY 'Screen Section: Use for interactive terminal applications'.

Follow usage guidelines: Working Storage for program variables, File Section for file definitions, Linkage Section for parameters, Local Storage for recursive programs, and Screen Section for terminal applications.

Data Section Best Practices

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       WORKING-STORAGE SECTION.
       01 DATA-SECTION-BEST-PRACTICES.
           05 ORGANIZED-CONSTANTS.
               10 C-MAX-RECORDS PIC 9(4) VALUE 1000.
               10 C-DEFAULT-VALUE PIC X(10) VALUE 'DEFAULT'.
               10 C-ERROR-MESSAGE PIC X(50) VALUE 'ERROR OCCURRED'.
           05 ORGANIZED-VARIABLES.
               10 WS-RECORD-COUNT PIC 9(6) VALUE 0.
               10 WS-TOTAL-AMOUNT PIC 9(9)V99 VALUE 0.
               10 WS-PROCESSING-FLAG PIC X VALUE 'N'.
           05 ORGANIZED-WORK-AREAS.
               10 TEMP-BUFFER PIC X(100).
               10 CALCULATION-AREA PIC 9(9)V99.
               10 ERROR-BUFFER PIC X(200).
       
       PROCEDURE DIVISION.
       PERFORM DEMONSTRATE-BEST-PRACTICES
       
       DEMONSTRATE-BEST-PRACTICES.
           DISPLAY 'Data Section Best Practices:'
           DISPLAY 'Group related data items together'
           DISPLAY 'Use meaningful names with appropriate prefixes'
           DISPLAY 'Initialize variables with appropriate values'
           DISPLAY 'Document data section purposes'
           DISPLAY 'Use consistent naming conventions'.

Follow best practices: group related data items, use meaningful names with prefixes (C- for constants, WS- for variables), initialize variables appropriately, document purposes, and maintain consistent naming conventions.

Section Performance Considerations

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       WORKING-STORAGE SECTION.
       01 PERFORMANCE-CONSIDERATIONS.
           05 EFFICIENT-DATA-TYPES.
               10 COMP-NUMERIC PIC 9(6) COMP.
               10 DISPLAY-NUMERIC PIC 9(6).
               10 PACKED-DECIMAL PIC 9(6)V99 COMP-3.
           05 APPROPRIATE-SIZES.
               10 SMALL-FIELD PIC X(10).
               10 MEDIUM-FIELD PIC X(50).
               10 LARGE-FIELD PIC X(200).
           05 MEMORY-OPTIMIZATION.
               10 GROUPED-DATA PIC X(100).
               10 ALIGNED-DATA PIC X(100).
       
       PROCEDURE DIVISION.
       PERFORM DEMONSTRATE-PERFORMANCE-CONSIDERATIONS
       
       DEMONSTRATE-PERFORMANCE-CONSIDERATIONS.
           DISPLAY 'Performance Considerations:'
           DISPLAY 'Use COMP for calculations, DISPLAY for I/O'
           DISPLAY 'Choose appropriate field sizes'
           DISPLAY 'Group related data for better memory usage'
           DISPLAY 'Consider data alignment for performance'.

Consider performance when organizing data sections: use COMP for calculations, DISPLAY for I/O operations, choose appropriate field sizes, group related data, and consider data alignment for optimal performance.

Data Representation

Data types and formats

Data Division

Data Division structure