In COBOL, the Linkage Section is a division within the program that defines data items used to pass information between the calling program and the called program or subprogram. It serves as a communication interface between different programs, allowing them to exchange data during program execution.
The Linkage Section is typically placed in the called program or subprogram and contains data items declared using the "LINKAGE SECTION" header. These data items are also known as "parameters" or "arguments." When the calling program invokes the called program, it passes values to these data items, which are then used within the called program.
Key uses of the Linkage Section are the following:
Passing Data: It allows the calling program to pass data or information to the called program for processing or manipulation.
Parameter Passing: It enables the passing of parameters (values or references) from the calling program to the called program, providing flexibility in data handling.
Returning Results: The called program can also use the Linkage Section to return results or computed values to the calling program.
Encapsulation: By using the Linkage Section, programs can be encapsulated as separate, reusable modules, enhancing program structure and maintainability.