The CALL statement identifies the program to be called, by giving either the program's filename or the program's program-name. This program-name is defined in its PROGRAM-ID paragraph.
In general, make the program-name the same as the filename. In other words, in the program's PROGRAM-ID paragraph, specify the program's filename without its extension. This enables you to call the program using this common name, without knowing whether the name is the filename or the program name. This gives you the flexibility to change how the program is linked, and yet still call it successfully.
The CALL statement locates called programs differently depending on how they are linked:
If you make the program name the same as the filename, you can quote that name in the CALL statement, and it will call the program whether it is statically and dynamically linked.