Structuring complex applications

Using subprograms
Many applications consist of several separately compiled programs linked together. A run unit (the COBOL term that is synonymous with the Language Environment® term enclave) includes one or more object programs and can include object programs written in other Language Environment member languages.
Sharing data
If a run unit consists of several separately compiled programs that call each other, the programs must be able to communicate with each other. They also usually need access to common data.
Creating a DLL or a DLL application
Creating a dynamic link library (DLL) or a DLL application is similar to creating a regular COBOL application. It involves writing, compiling, and linking your source code.
Preparing COBOL programs for multithreading
You can run COBOL programs in multiple threads within a process under batch, TSO, IMS, or z/OS® UNIX.

Parent topic: Programming guide