Creating Large Systems
All the programs you have seen so far in this book have been small stand-alone programs. But a large software system is not usually written as a single monolithic program. Instead, it consists of a main program and many independently compiled subprograms, linked together to form one executable run-unit. In COBOL, a program that is invoked from another program is called a subprogram. In other languages, these might be called procedures or methods.