CBL_THREAD_SELF

Stores the thread identifier of the current thread.

Syntax:
call "CBL_THREAD_SELF" using by reference thread-id
Parameters:
Using call prototype (see Library Routines - Key) Picture (32-bit systems)
thread-id cblt-pointer usage pointer.
On Entry:
thread-id A pointer to the thread identifier.
On Exit:
return-code A value indicating success or otherwise. See RETURN-CODE Values For Thread-control Routines
Comments:

The run-time system returns the thread identifier and stores it in thread-id.

You can check that the run-time system under which your program is running supports multi-threading by a call to CBL_THREAD_SELF:

Using CBL_THREAD_SELF to Check Operating System

See Also: