Some programs run so often we take special efforts to make sure that only one copy of the program needs to be loaded into memory, no matter how many users are running it concurrently. That’s what reentrant programming is all about. We can do this by dynamically allocating storage for all the parts of our program that might change. Each user gets their own copy of dynamic storage.
Want to get your assembler program to run in the Language Environment? It needs to be reentrant. Future posts will cover COBOL calling Assembler and Assembler calling COBOL in the Language Environment, but to follow along, you first have to learn how to write assembler reentrantly.
Some programmers write all their programs in a reentrant style. There’s not a lot of extra overhead. Want to give it a try? I’ve posted a video about how it works here and in the assembler video course. There’s also a sample reentrant program you can start with here. The video explains in detail how the program works.