COBOL Tutorial

COBOL SYSTEM-DEFAULT - Quick Reference

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Overview

The SYSTEM-DEFAULT feature in COBOL provides access to system-provided default values, settings, and configuration parameters. It allows programs to retrieve and use system defaults, making them more portable and adaptable to different system configurations.

Purpose and Usage

System configuration access - Retrieve system configuration values
Default settings - Access system default parameters
Environment variables - Read system environment settings
System limits - Access system-imposed limits and boundaries
Portability - Improve program portability across systems

SYSTEM-DEFAULT vs Hardcoded Values

Hardcoded: BUFFER-SIZE = 4096

SYSTEM-DEFAULT: BUFFER-SIZE = SYSTEM-DEFAULT-BUFFER

Result: Adaptable to different system configurations

SYSTEM-DEFAULT provides system-specific values instead of hardcoded constants.

Syntax and Usage

SYSTEM-DEFAULT is used in the PROCEDURE DIVISION to access system-provided default values and configuration parameters.

Basic SYSTEM-DEFAULT Syntax

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* Basic SYSTEM-DEFAULT syntax examples
       PROCEDURE DIVISION.
       
       * Access system default buffer size
       MOVE SYSTEM-DEFAULT-BUFFER-SIZE TO BUFFER-SIZE
       
       * Access system default timeout
       MOVE SYSTEM-DEFAULT-TIMEOUT TO TIMEOUT-VALUE
       
       * Access system default currency
       MOVE SYSTEM-DEFAULT-CURRENCY TO CURRENCY-CODE
       
       * Access system default language
       MOVE SYSTEM-DEFAULT-LANGUAGE TO LANGUAGE-CODE
       
       * Access system default date format
       MOVE SYSTEM-DEFAULT-DATE-FORMAT TO DATE-FORMAT
       
       * Access system default time format
       MOVE SYSTEM-DEFAULT-TIME-FORMAT TO TIME-FORMAT

Basic SYSTEM-DEFAULT operations for accessing system values.

Complete SYSTEM-DEFAULT Program Example

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* Complete COBOL program demonstrating SYSTEM-DEFAULT usage
       IDENTIFICATION DIVISION.
       PROGRAM-ID. SYSTEM-DEFAULT-DEMO.
       
       ENVIRONMENT DIVISION.
       CONFIGURATION SECTION.
       
       DATA DIVISION.
       WORKING-STORAGE SECTION.
       01  SYSTEM-CONFIG.
           05  BUFFER-SIZE       PIC 9(6).
           05  TIMEOUT-VALUE     PIC 9(4).
           05  CURRENCY-CODE     PIC X(3).
           05  LANGUAGE-CODE     PIC X(2).
           05  DATE-FORMAT       PIC X(10).
           05  TIME-FORMAT       PIC X(10).
       
       01  SYSTEM-LIMITS.
           05  MAX-FILES         PIC 9(3).
           05  MAX-RECORDS       PIC 9(8).
           05  MAX-MEMORY        PIC 9(10).
       
       PROCEDURE DIVISION.
       MAIN-LOGIC.
           PERFORM LOAD-SYSTEM-DEFAULTS
           PERFORM DISPLAY-SYSTEM-CONFIG
           PERFORM USE-SYSTEM-DEFAULTS
           STOP RUN.
       
       LOAD-SYSTEM-DEFAULTS.
           * Load system default configuration values
           MOVE SYSTEM-DEFAULT-BUFFER-SIZE TO BUFFER-SIZE
           MOVE SYSTEM-DEFAULT-TIMEOUT TO TIMEOUT-VALUE
           MOVE SYSTEM-DEFAULT-CURRENCY TO CURRENCY-CODE
           MOVE SYSTEM-DEFAULT-LANGUAGE TO LANGUAGE-CODE
           MOVE SYSTEM-DEFAULT-DATE-FORMAT TO DATE-FORMAT
           MOVE SYSTEM-DEFAULT-TIME-FORMAT TO TIME-FORMAT.
       
       DISPLAY-SYSTEM-CONFIG.
           DISPLAY "System Configuration:"
           DISPLAY "Buffer Size: " BUFFER-SIZE
           DISPLAY "Timeout: " TIMEOUT-VALUE
           DISPLAY "Currency: " CURRENCY-CODE
           DISPLAY "Language: " LANGUAGE-CODE
           DISPLAY "Date Format: " DATE-FORMAT
           DISPLAY "Time Format: " TIME-FORMAT.
       
       USE-SYSTEM-DEFAULTS.
           * Use system defaults in program logic
           IF BUFFER-SIZE > 0
               PERFORM CONFIGURE-BUFFER
           END-IF
           
           IF TIMEOUT-VALUE > 0
               PERFORM SET-TIMEOUT
           END-IF
           
           * Use system currency for financial calculations
           PERFORM FORMAT-CURRENCY.
       
       CONFIGURE-BUFFER.
           DISPLAY "Configuring buffer with size: " BUFFER-SIZE.
       
       SET-TIMEOUT.
           DISPLAY "Setting timeout to: " TIMEOUT-VALUE " seconds".
       
       FORMAT-CURRENCY.
           DISPLAY "Using currency format: " CURRENCY-CODE.

The program demonstrates loading and using system default values.

Advanced SYSTEM-DEFAULT Usage

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* Advanced SYSTEM-DEFAULT usage with error handling
       PROCEDURE DIVISION.
       
       LOAD-SYSTEM-CONFIGURATION.
           * Load system defaults with fallback values
           PERFORM GET-SYSTEM-BUFFER-SIZE
           PERFORM GET-SYSTEM-TIMEOUT
           PERFORM GET-SYSTEM-CURRENCY
           PERFORM GET-SYSTEM-LANGUAGE.
       
       GET-SYSTEM-BUFFER-SIZE.
           * Try to get system default, use fallback if not available
                       IF SYSTEM-DEFAULT-BUFFER-SIZE > 0
               MOVE SYSTEM-DEFAULT-BUFFER-SIZE TO BUFFER-SIZE
           ELSE
               MOVE 4096 TO BUFFER-SIZE  * Fallback value
               DISPLAY "Using fallback buffer size: " BUFFER-SIZE
           END-IF.
       
       GET-SYSTEM-TIMEOUT.
           IF SYSTEM-DEFAULT-TIMEOUT > 0
               MOVE SYSTEM-DEFAULT-TIMEOUT TO TIMEOUT-VALUE
           ELSE
               MOVE 30 TO TIMEOUT-VALUE  * Fallback value
               DISPLAY "Using fallback timeout: " TIMEOUT-VALUE
           END-IF.
       
       GET-SYSTEM-CURRENCY.
           IF SYSTEM-DEFAULT-CURRENCY NOT = SPACES
               MOVE SYSTEM-DEFAULT-CURRENCY TO CURRENCY-CODE
           ELSE
               MOVE "USD" TO CURRENCY-CODE  * Fallback value
               DISPLAY "Using fallback currency: " CURRENCY-CODE
           END-IF.
       
       GET-SYSTEM-LANGUAGE.
           IF SYSTEM-DEFAULT-LANGUAGE NOT = SPACES
               MOVE SYSTEM-DEFAULT-LANGUAGE TO LANGUAGE-CODE
           ELSE
               MOVE "EN" TO LANGUAGE-CODE  * Fallback value
               DISPLAY "Using fallback language: " LANGUAGE-CODE
           END-IF.

Advanced SYSTEM-DEFAULT usage with error handling and fallback values.

Common Use Cases

SYSTEM-DEFAULT is essential in various scenarios where programs need to adapt to different system configurations and use system-provided values.

System Configuration Management

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* System configuration management using SYSTEM-DEFAULT
       IDENTIFICATION DIVISION.
       PROGRAM-ID. SYSTEM-CONFIG-MANAGER.
       
       DATA DIVISION.
       WORKING-STORAGE SECTION.
       01  SYSTEM-SETTINGS.
           05  DEFAULT-BUFFER    PIC 9(6).
           05  DEFAULT-TIMEOUT   PIC 9(4).
           05  DEFAULT-CURRENCY  PIC X(3).
           05  DEFAULT-LANGUAGE  PIC X(2).
       
       PROCEDURE DIVISION.
       MAIN-LOGIC.
           PERFORM LOAD-SYSTEM-SETTINGS
           PERFORM CONFIGURE-APPLICATION
           PERFORM START-APPLICATION
           STOP RUN.
       
       LOAD-SYSTEM-SETTINGS.
           * Load all system default settings
           MOVE SYSTEM-DEFAULT-BUFFER-SIZE TO DEFAULT-BUFFER
           MOVE SYSTEM-DEFAULT-TIMEOUT TO DEFAULT-TIMEOUT
           MOVE SYSTEM-DEFAULT-CURRENCY TO DEFAULT-CURRENCY
           MOVE SYSTEM-DEFAULT-LANGUAGE TO DEFAULT-LANGUAGE
           
           DISPLAY "System settings loaded:"
           DISPLAY "Buffer: " DEFAULT-BUFFER
           DISPLAY "Timeout: " DEFAULT-TIMEOUT
           DISPLAY "Currency: " DEFAULT-CURRENCY
           DISPLAY "Language: " DEFAULT-LANGUAGE.
       
       CONFIGURE-APPLICATION.
           * Configure application using system defaults
           PERFORM SET-BUFFER-CONFIGURATION
           PERFORM SET-TIMEOUT-CONFIGURATION
           PERFORM SET-CURRENCY-CONFIGURATION
           PERFORM SET-LANGUAGE-CONFIGURATION.
       
       SET-BUFFER-CONFIGURATION.
           IF DEFAULT-BUFFER > 0
               MOVE DEFAULT-BUFFER TO APPLICATION-BUFFER-SIZE
               DISPLAY "Buffer configured: " APPLICATION-BUFFER-SIZE
           END-IF.

System configuration management using SYSTEM-DEFAULT values.

Cross-Platform Compatibility

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* Cross-platform compatibility using SYSTEM-DEFAULT
       IDENTIFICATION DIVISION.
       PROGRAM-ID. CROSS-PLATFORM-APP.
       
       DATA DIVISION.
       WORKING-STORAGE SECTION.
       01  PLATFORM-CONFIG.
           05  PLATFORM-TYPE    PIC X(10).
           05  PLATFORM-VERSION PIC X(10).
           05  PLATFORM-ARCH    PIC X(10).
       
       PROCEDURE DIVISION.
       MAIN-LOGIC.
           PERFORM DETECT-PLATFORM
           PERFORM LOAD-PLATFORM-DEFAULTS
           PERFORM ADAPT-TO-PLATFORM
           STOP RUN.
       
       DETECT-PLATFORM.
           * Detect platform and load appropriate defaults
           MOVE SYSTEM-DEFAULT-PLATFORM TO PLATFORM-TYPE
           MOVE SYSTEM-DEFAULT-VERSION TO PLATFORM-VERSION
           MOVE SYSTEM-DEFAULT-ARCHITECTURE TO PLATFORM-ARCH
           
           DISPLAY "Platform detected:"
           DISPLAY "Type: " PLATFORM-TYPE
           DISPLAY "Version: " PLATFORM-VERSION
           DISPLAY "Architecture: " PLATFORM-ARCH.
       
       LOAD-PLATFORM-DEFAULTS.
           * Load platform-specific default values
           IF PLATFORM-TYPE = "WINDOWS"
               PERFORM LOAD-WINDOWS-DEFAULTS
           ELSE IF PLATFORM-TYPE = "UNIX"
               PERFORM LOAD-UNIX-DEFAULTS
           ELSE IF PLATFORM-TYPE = "MAINFRAME"
               PERFORM LOAD-MAINFRAME-DEFAULTS
           ELSE
               PERFORM LOAD-GENERIC-DEFAULTS
           END-IF.
       
       LOAD-WINDOWS-DEFAULTS.
           MOVE SYSTEM-DEFAULT-WINDOWS-BUFFER TO BUFFER-SIZE
           MOVE SYSTEM-DEFAULT-WINDOWS-TIMEOUT TO TIMEOUT-VALUE.
       
       LOAD-UNIX-DEFAULTS.
           MOVE SYSTEM-DEFAULT-UNIX-BUFFER TO BUFFER-SIZE
           MOVE SYSTEM-DEFAULT-UNIX-TIMEOUT TO TIMEOUT-VALUE.

Cross-platform compatibility using SYSTEM-DEFAULT for different platforms.

Environment Adaptation

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* Environment adaptation using SYSTEM-DEFAULT
       IDENTIFICATION DIVISION.
       PROGRAM-ID. ENVIRONMENT-ADAPTER.
       
       DATA DIVISION.
       WORKING-STORAGE SECTION.
       01  ENVIRONMENT-CONFIG.
           05  ENV-TYPE         PIC X(10).
           05  ENV-LEVEL        PIC X(10).
           05  ENV-SECURITY     PIC X(10).
       
       PROCEDURE DIVISION.
       MAIN-LOGIC.
           PERFORM DETECT-ENVIRONMENT
           PERFORM LOAD-ENVIRONMENT-DEFAULTS
           PERFORM ADAPT-TO-ENVIRONMENT
           STOP RUN.
       
       DETECT-ENVIRONMENT.
           * Detect environment and load appropriate defaults
           MOVE SYSTEM-DEFAULT-ENVIRONMENT TO ENV-TYPE
           MOVE SYSTEM-DEFAULT-ENVIRONMENT-LEVEL TO ENV-LEVEL
           MOVE SYSTEM-DEFAULT-SECURITY-LEVEL TO ENV-SECURITY.
       
       LOAD-ENVIRONMENT-DEFAULTS.
           * Load environment-specific default values
           IF ENV-TYPE = "DEVELOPMENT"
               PERFORM LOAD-DEV-DEFAULTS
           ELSE IF ENV-TYPE = "TESTING"
               PERFORM LOAD-TEST-DEFAULTS
           ELSE IF ENV-TYPE = "PRODUCTION"
               PERFORM LOAD-PROD-DEFAULTS
           END-IF.
       
       LOAD-DEV-DEFAULTS.
           MOVE SYSTEM-DEFAULT-DEV-BUFFER TO BUFFER-SIZE
           MOVE SYSTEM-DEFAULT-DEV-TIMEOUT TO TIMEOUT-VALUE
           MOVE SYSTEM-DEFAULT-DEV-LOG-LEVEL TO LOG-LEVEL.
       
       LOAD-PROD-DEFAULTS.
           MOVE SYSTEM-DEFAULT-PROD-BUFFER TO BUFFER-SIZE
           MOVE SYSTEM-DEFAULT-PROD-TIMEOUT TO TIMEOUT-VALUE
           MOVE SYSTEM-DEFAULT-PROD-LOG-LEVEL TO LOG-LEVEL.

Environment adaptation using SYSTEM-DEFAULT for different environments.

Best Practices and Tips

Following these best practices ensures effective use of SYSTEM-DEFAULT in COBOL applications for better portability and adaptability.

SYSTEM-DEFAULT Best Practices

Always provide fallback values - Handle cases where system defaults are unavailable
Test on different systems - Verify behavior across different system configurations
Document system dependencies - Clearly document which system defaults are used
Handle missing defaults - Provide appropriate error handling for missing defaults
Use meaningful fallbacks - Choose sensible fallback values when defaults are unavailable
Validate system values - Verify that system defaults are within expected ranges

Common SYSTEM-DEFAULT Values

System Default	Description	Common Values
BUFFER-SIZE	Default buffer size for I/O operations	4096, 8192, 16384
TIMEOUT	Default timeout for operations	30, 60, 300 seconds
CURRENCY	Default currency code	USD, EUR, GBP
LANGUAGE	Default language code	EN, ES, FR, DE
DATE-FORMAT	Default date format	MM/DD/YYYY, DD/MM/YYYY
TIME-FORMAT	Default time format	HH:MM:SS, HH:MM

Portability Considerations

System differences - Different systems may provide different default values
Version variations - System defaults may change between versions
Environment factors - Defaults may vary based on environment configuration
Fallback strategy - Always have a fallback strategy for missing defaults
Testing strategy - Test on multiple system configurations
Documentation - Document system dependencies and fallback values

SYSTEM-DEFAULT Quick Reference

Aspect	Description	Example
Location	PROCEDURE DIVISION	During program execution
Basic Syntax	MOVE SYSTEM-DEFAULT-[TYPE] TO variable	MOVE SYSTEM-DEFAULT-BUFFER-SIZE TO BUFFER
Error Handling	Check for valid values and provide fallbacks	IF SYSTEM-DEFAULT-BUFFER > 0
Types	Configuration, limits, settings	BUFFER-SIZE, TIMEOUT, CURRENCY
Benefits	Portability, adaptability	System-independent code

Test Your Knowledge

1. What is the primary purpose of SYSTEM-DEFAULT in COBOL?

To define arithmetic operations
To access system default values, settings, and configuration parameters
To control file operations
To define data types

2. Where is SYSTEM-DEFAULT typically used in a COBOL program?

In the DATA DIVISION for system data definitions
In the PROCEDURE DIVISION to access system defaults
In the ENVIRONMENT DIVISION for system configuration
In the IDENTIFICATION DIVISION

3. What types of values can SYSTEM-DEFAULT provide?

Only numeric constants
Only alphanumeric constants
System settings, configuration values, and default parameters
Only file status codes

4. How does SYSTEM-DEFAULT improve program portability?

It has no effect on portability
By using system-provided defaults instead of hardcoded values
By reducing program size
By improving compilation speed

5. Which of the following is a common use of SYSTEM-DEFAULT?

File sorting operations
Accessing system configuration values, default settings, and environment parameters
Database operations
Mathematical calculations

COBOL Tutorial

COBOL SYSTEM-DEFAULT - Quick Reference

Overview

Purpose and Usage

SYSTEM-DEFAULT vs Hardcoded Values

Syntax and Usage

Basic SYSTEM-DEFAULT Syntax

Complete SYSTEM-DEFAULT Program Example

Advanced SYSTEM-DEFAULT Usage

Common Use Cases

System Configuration Management

Cross-Platform Compatibility

Environment Adaptation

Best Practices and Tips

SYSTEM-DEFAULT Best Practices

Common SYSTEM-DEFAULT Values

Portability Considerations

SYSTEM-DEFAULT Quick Reference

Test Your Knowledge

Frequently Asked Questions

Related Concepts

System Configuration

Environment Variables

Cross-Platform Development

System Integration

Configuration Management

Related Pages

COBOL Tutorial

COBOL SYSTEM-DEFAULT - Quick Reference

Overview

Purpose and Usage

SYSTEM-DEFAULT vs Hardcoded Values

Syntax and Usage

Basic SYSTEM-DEFAULT Syntax

Complete SYSTEM-DEFAULT Program Example

Advanced SYSTEM-DEFAULT Usage

Common Use Cases

System Configuration Management

Cross-Platform Compatibility

Environment Adaptation

Best Practices and Tips

SYSTEM-DEFAULT Best Practices

Common SYSTEM-DEFAULT Values

Portability Considerations

SYSTEM-DEFAULT Quick Reference

Test Your Knowledge

Frequently Asked Questions

What is SYSTEM-DEFAULT and how is it used in COBOL?

What are the main SYSTEM-DEFAULT operations available in COBOL?

How do you implement SYSTEM-DEFAULT in COBOL programs?

What are the best practices for using SYSTEM-DEFAULT in COBOL programs?

How does SYSTEM-DEFAULT support program portability and adaptability?

Related Concepts

System Configuration

Environment Variables

Cross-Platform Development

System Integration

Configuration Management

Related Pages