You can specify that a program is not a multi-threading program, by omitting any of the multi-threading Compiler directives when you compile your program.
If you do this, system work areas are allocated statically, and are thus subject to contention. This approach has several advantages, call speed and efficient stack usage among them, but it is up to your application to make sure that only one thread executes within a non-multi-threading program at a time. This can be accomplished through implicit program logic in any calling program; for example, when the application, by design, has only one thread calling a non-multi-threaded program. Alternatively, one of the synchronization primitives (such as a mutex) can be locked in the calling program just before the called program is entered and then unlocked when the called program has returned.