COBOL Tutorial

COBOL SAME Clause - Quick Reference

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Overview

The SAME clause is used to specify that multiple files share the same record area in memory. This conserves memory by allowing different files to use the same physical memory location for their record descriptions.

Purpose and Usage

Memory conservation - Share record areas between files
Resource optimization - Reduce memory usage
File management - Efficient file handling
Batch processing - Optimize batch operations
Storage efficiency - Maximize memory utilization

Memory Sharing Concept

Without SAME:

File A: [Record Area A]

File B: [Record Area B]

File C: [Record Area C]

With SAME:

File A: [Shared Record Area]

File B: [Shared Record Area]

File C: [Shared Record Area]

SAME allows multiple files to share the same memory area.

Syntax

The SAME clause is used in the FILE SECTION to specify shared record areas.

Basic Syntax

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* Basic SAME clause syntax
FD  file-name-1.
01  record-name-1.
    * record description
 
FD  file-name-2 SAME RECORD AREA AS file-name-1.
01  record-name-2.
    * record description
 
* Complete example
IDENTIFICATION DIVISION.
PROGRAM-ID. SAME-EXAMPLE.
 
ENVIRONMENT DIVISION.
INPUT-OUTPUT SECTION.
FILE-CONTROL.
    SELECT INPUT-FILE ASSIGN TO "INPUT.DAT"
        ORGANIZATION IS SEQUENTIAL.
    SELECT OUTPUT-FILE ASSIGN TO "OUTPUT.DAT"
        ORGANIZATION IS SEQUENTIAL.
    SELECT TEMP-FILE ASSIGN TO "TEMP.DAT"
        ORGANIZATION IS SEQUENTIAL.
 
DATA DIVISION.
FILE SECTION.
FD  INPUT-FILE.
01  INPUT-RECORD.
    05  CUSTOMER-ID    PIC 9(6).
    05  CUSTOMER-NAME  PIC X(30).
    05  CUSTOMER-BALANCE PIC 9(8)V99.
 
FD  OUTPUT-FILE SAME RECORD AREA AS INPUT-FILE.
01  OUTPUT-RECORD.
    05  CUST-ID        PIC 9(6).
    05  CUST-NAME      PIC X(30).
    05  CUST-BALANCE   PIC 9(8)V99.
 
FD  TEMP-FILE SAME RECORD AREA AS INPUT-FILE.
01  TEMP-RECORD.
    05  TEMP-ID        PIC 9(6).
    05  TEMP-NAME      PIC X(30).
    05  TEMP-BALANCE   PIC 9(8)V99.
 
PROCEDURE DIVISION.
MAIN-LOGIC.
    OPEN INPUT INPUT-FILE
    OPEN OUTPUT OUTPUT-FILE
    OPEN OUTPUT TEMP-FILE
    
    PERFORM PROCESS-RECORDS
    
    CLOSE INPUT-FILE OUTPUT-FILE TEMP-FILE
    STOP RUN.
 
PROCESS-RECORDS.
    READ INPUT-FILE
        AT END
            EXIT PARAGRAPH
    END-READ
    
    * Process record using shared area
    IF CUSTOMER-BALANCE > 1000
        WRITE OUTPUT-RECORD FROM INPUT-RECORD
    ELSE
        WRITE TEMP-RECORD FROM INPUT-RECORD
    END-IF
    
    GO TO PROCESS-RECORDS.

SAME RECORD AREA allows files to share memory space.

SAME vs Separate Record Areas

Approach	Memory Usage	File Access
SAME RECORD AREA	Conserved	Sequential
Separate Areas	More memory	Simultaneous
Mixed Approach	Balanced	Flexible

Practical Examples

These examples demonstrate how to use the SAME clause effectively in different file processing scenarios.

Data Processing Pipeline

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IDENTIFICATION DIVISION.
PROGRAM-ID. DATA-PIPELINE.
 
ENVIRONMENT DIVISION.
INPUT-OUTPUT SECTION.
FILE-CONTROL.
    SELECT RAW-DATA ASSIGN TO "RAW.DAT"
        ORGANIZATION IS SEQUENTIAL.
    SELECT VALID-DATA ASSIGN TO "VALID.DAT"
        ORGANIZATION IS SEQUENTIAL.
    SELECT INVALID-DATA ASSIGN TO "INVALID.DAT"
        ORGANIZATION IS SEQUENTIAL.
    SELECT PROCESSED-DATA ASSIGN TO "PROCESSED.DAT"
        ORGANIZATION IS SEQUENTIAL.
 
DATA DIVISION.
FILE SECTION.
FD  RAW-DATA.
01  RAW-RECORD.
    05  DATA-ID       PIC 9(6).
    05  DATA-VALUE    PIC X(50).
    05  DATA-STATUS   PIC X(1).
 
FD  VALID-DATA SAME RECORD AREA AS RAW-DATA.
01  VALID-RECORD.
    05  VALID-ID      PIC 9(6).
    05  VALID-VALUE   PIC X(50).
    05  VALID-STATUS  PIC X(1).
 
FD  INVALID-DATA SAME RECORD AREA AS RAW-DATA.
01  INVALID-RECORD.
    05  INVALID-ID    PIC 9(6).
    05  INVALID-VALUE PIC X(50).
    05  INVALID-STATUS PIC X(1).
 
FD  PROCESSED-DATA SAME RECORD AREA AS RAW-DATA.
01  PROCESSED-RECORD.
    05  PROCESSED-ID  PIC 9(6).
    05  PROCESSED-VALUE PIC X(50).
    05  PROCESSED-STATUS PIC X(1).
 
PROCEDURE DIVISION.
MAIN-LOGIC.
    OPEN INPUT RAW-DATA
    OPEN OUTPUT VALID-DATA INVALID-DATA PROCESSED-DATA
    
    PERFORM PROCESS-DATA-PIPELINE
    
    CLOSE RAW-DATA VALID-DATA INVALID-DATA PROCESSED-DATA
    STOP RUN.
 
PROCESS-DATA-PIPELINE.
    READ RAW-DATA
        AT END
            EXIT PARAGRAPH
    END-READ
    
    * Validate data
    IF DATA-STATUS = "V"
        WRITE VALID-RECORD FROM RAW-RECORD
        PERFORM PROCESS-VALID-DATA
    ELSE
        WRITE INVALID-RECORD FROM RAW-RECORD
    END-IF
    
    GO TO PROCESS-DATA-PIPELINE.
 
PROCESS-VALID-DATA.
    * Process valid data using shared record area
    MOVE "P" TO DATA-STATUS
    WRITE PROCESSED-RECORD FROM RAW-RECORD.

SAME enables efficient data processing pipelines.

File Conversion

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* File conversion with SAME RECORD AREA
DATA DIVISION.
FILE SECTION.
FD  OLD-FORMAT.
01  OLD-RECORD.
    05  OLD-ID        PIC 9(6).
    05  OLD-NAME      PIC X(20).
    05  OLD-ADDRESS   PIC X(30).
    05  OLD-PHONE     PIC X(10).
 
FD  NEW-FORMAT SAME RECORD AREA AS OLD-FORMAT.
01  NEW-RECORD.
    05  NEW-ID        PIC 9(6).
    05  NEW-NAME      PIC X(25).
    05  NEW-ADDRESS   PIC X(40).
    05  NEW-PHONE     PIC X(15).
    05  NEW-EMAIL     PIC X(30).
 
FD  ERROR-FILE SAME RECORD AREA AS OLD-FORMAT.
01  ERROR-RECORD.
    05  ERROR-ID      PIC 9(6).
    05  ERROR-NAME    PIC X(20).
    05  ERROR-ADDRESS PIC X(30).
    05  ERROR-PHONE   PIC X(10).
 
PROCEDURE DIVISION.
CONVERT-FILES.
    OPEN INPUT OLD-FORMAT
    OPEN OUTPUT NEW-FORMAT ERROR-FILE
    
    PERFORM CONVERT-RECORDS
    
    CLOSE OLD-FORMAT NEW-FORMAT ERROR-FILE.
 
CONVERT-RECORDS.
    READ OLD-FORMAT
        AT END
            EXIT PARAGRAPH
    END-READ
    
    * Convert record format
    IF OLD-NAME NOT = SPACES
        MOVE OLD-ID TO NEW-ID
        MOVE OLD-NAME TO NEW-NAME
        MOVE OLD-ADDRESS TO NEW-ADDRESS
        MOVE OLD-PHONE TO NEW-PHONE
        MOVE SPACES TO NEW-EMAIL
        WRITE NEW-RECORD
    ELSE
        WRITE ERROR-RECORD FROM OLD-RECORD
    END-IF
    
    GO TO CONVERT-RECORDS.

SAME facilitates efficient file format conversion.

Data Filtering

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* Data filtering with SAME RECORD AREA
DATA DIVISION.
FILE SECTION.
FD  MASTER-FILE.
01  MASTER-RECORD.
    05  MASTER-ID     PIC 9(6).
    05  MASTER-NAME   PIC X(30).
    05  MASTER-STATUS PIC X(1).
    05  MASTER-BALANCE PIC 9(8)V99.
 
FD  ACTIVE-FILE SAME RECORD AREA AS MASTER-FILE.
01  ACTIVE-RECORD.
    05  ACTIVE-ID     PIC 9(6).
    05  ACTIVE-NAME   PIC X(30).
    05  ACTIVE-STATUS PIC X(1).
    05  ACTIVE-BALANCE PIC 9(8)V99.
 
FD  INACTIVE-FILE SAME RECORD AREA AS MASTER-FILE.
01  INACTIVE-RECORD.
    05  INACTIVE-ID   PIC 9(6).
    05  INACTIVE-NAME PIC X(30).
    05  INACTIVE-STATUS PIC X(1).
    05  INACTIVE-BALANCE PIC 9(8)V99.
 
FD  HIGH-BALANCE-FILE SAME RECORD AREA AS MASTER-FILE.
01  HIGH-BALANCE-RECORD.
    05  HIGH-BALANCE-ID PIC 9(6).
    05  HIGH-BALANCE-NAME PIC X(30).
    05  HIGH-BALANCE-STATUS PIC X(1).
    05  HIGH-BALANCE-AMOUNT PIC 9(8)V99.
 
PROCEDURE DIVISION.
FILTER-DATA.
    OPEN INPUT MASTER-FILE
    OPEN OUTPUT ACTIVE-FILE INACTIVE-FILE HIGH-BALANCE-FILE
    
    PERFORM FILTER-RECORDS
    
    CLOSE MASTER-FILE ACTIVE-FILE INACTIVE-FILE HIGH-BALANCE-FILE.
 
FILTER-RECORDS.
    READ MASTER-FILE
        AT END
            EXIT PARAGRAPH
    END-READ
    
    * Filter based on status and balance
    EVALUATE MASTER-STATUS
        WHEN "A"
            WRITE ACTIVE-RECORD FROM MASTER-RECORD
            IF MASTER-BALANCE > 10000
                WRITE HIGH-BALANCE-RECORD FROM MASTER-RECORD
            END-IF
        WHEN "I"
            WRITE INACTIVE-RECORD FROM MASTER-RECORD
        WHEN OTHER
            WRITE INACTIVE-RECORD FROM MASTER-RECORD
    END-EVALUATE
    
    GO TO FILTER-RECORDS.

SAME enables efficient data filtering operations.

Backup and Archive

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* Backup and archive with SAME RECORD AREA
DATA DIVISION.
FILE SECTION.
FD  CURRENT-FILE.
01  CURRENT-RECORD.
    05  CURRENT-ID    PIC 9(6).
    05  CURRENT-DATA  PIC X(100).
    05  CURRENT-DATE  PIC X(8).
 
FD  BACKUP-FILE SAME RECORD AREA AS CURRENT-FILE.
01  BACKUP-RECORD.
    05  BACKUP-ID     PIC 9(6).
    05  BACKUP-DATA   PIC X(100).
    05  BACKUP-DATE   PIC X(8).
 
FD  ARCHIVE-FILE SAME RECORD AREA AS CURRENT-FILE.
01  ARCHIVE-RECORD.
    05  ARCHIVE-ID    PIC 9(6).
    05  ARCHIVE-DATA  PIC X(100).
    05  ARCHIVE-DATE  PIC X(8).
 
PROCEDURE DIVISION.
BACKUP-AND-ARCHIVE.
    OPEN INPUT CURRENT-FILE
    OPEN OUTPUT BACKUP-FILE ARCHIVE-FILE
    
    PERFORM PROCESS-RECORDS
    
    CLOSE CURRENT-FILE BACKUP-FILE ARCHIVE-FILE.
 
PROCESS-RECORDS.
    READ CURRENT-FILE
        AT END
            EXIT PARAGRAPH
    END-READ
    
    * Create backup
    WRITE BACKUP-RECORD FROM CURRENT-RECORD
    
    * Archive old records
    IF CURRENT-DATE < "20230101"
        WRITE ARCHIVE-RECORD FROM CURRENT-RECORD
    END-IF
    
    GO TO PROCESS-RECORDS.

SAME facilitates efficient backup and archive operations.

Best Practices and Considerations

Understanding best practices ensures effective use of the SAME clause.

Best Practices

Use with compatible records - Ensure record structures are compatible
Plan file operations - Only one file can be active at a time
Close files properly - Ensure proper file closure
Test thoroughly - Verify SAME behavior with your data
Document usage - Clearly document SAME relationships
Consider alternatives - Evaluate when SAME is appropriate

Use Case Comparison

Use Case	SAME Benefits	Considerations
Memory Conservation	Reduces memory usage	Sequential file access
Batch Processing	Efficient processing	File switching overhead
Data Conversion	Shared record area	Record compatibility
File Filtering	Multiple output files	Sequential processing

Performance Considerations

Memory efficiency - SAME conserves memory resources
File switching - Only one file active at a time
Processing overhead - File open/close operations
Record compatibility - Must ensure compatible structures
Error handling - Careful handling of shared areas

SAME Clause Quick Reference

Usage	Syntax	Example
Basic SAME	FD file2 SAME RECORD AREA AS file1	FD OUTPUT SAME RECORD AREA AS INPUT
Multiple files	FD file3 SAME RECORD AREA AS file1	FD TEMP SAME RECORD AREA AS INPUT
Different names	FD file2 SAME RECORD AREA AS file1	FD NEW SAME RECORD AREA AS OLD
File operations	OPEN/CLOSE files sequentially	OPEN INPUT1 CLOSE INPUT1 OPEN INPUT2
Record sharing	Use shared record area	MOVE data between files

Test Your Knowledge

1. What is the primary purpose of the SAME clause in COBOL?

To compare two values for equality
To share record areas between files
To create identical copies of data
To sort data in the same order

2. In which COBOL section is the SAME clause typically used?

IDENTIFICATION DIVISION
ENVIRONMENT DIVISION
DATA DIVISION
PROCEDURE DIVISION

3. What is the main benefit of using the SAME clause?

Improved performance
Memory conservation
Better data organization
Enhanced security

4. Can SAME be used with all file organization types?

Yes, with all file types
Only with sequential files
Only with indexed files
Only with relative files

5. What happens when files share the same record area?

They become identical
They share the same memory location
They are automatically synchronized
They are merged into one file

Frequently Asked Questions

Related Concepts

File Processing

Understanding file processing in COBOL.

File Organization

Different file organization types in COBOL.

Memory Management

Memory management techniques in COBOL.

Batch Processing

Batch processing with file operations.

Data Division

Understanding the DATA DIVISION structure.

RUN Statement SCREEN Clause

COBOL Tutorial

COBOL SAME Clause - Quick Reference

Overview

Purpose and Usage

Memory Sharing Concept

Syntax

Basic Syntax

SAME vs Separate Record Areas

Practical Examples

Data Processing Pipeline

File Conversion

Data Filtering

Backup and Archive

Best Practices and Considerations

Best Practices

Use Case Comparison

Performance Considerations

SAME Clause Quick Reference

Test Your Knowledge

Frequently Asked Questions

What is the difference between SAME RECORD AREA and separate record areas?

How do you implement the SAME clause in a COBOL program?

Can you use SAME with files that have different record structures?

What are some common use cases for the SAME clause?

How does the SAME clause affect program performance and memory usage?

Related Concepts

File Processing

File Organization

Memory Management

Batch Processing

Data Division

Related Pages