A thread is attached (or created) by the execution of the ATTACH statement. You can specify explicit characteristics for the thread if the defaults are not desired.
Arguments can be passed to the new thread just as you would pass arguments to a synchronous entry in a CALL statement.
Unless explicitly declared, the named variable is given a contextual declaration.
If the THREAD option is not specified, the attached thread cannot be stopped or waited upon by another thread.
If a thread is attached with the THREAD option, it should be detached using the DETACH statement (see Detaching a thread) to free all the system resources associated with the thread.
Operating system services must not be used directly to create a thread.
On z/OS, TSTACK is ignored, and the size of the stack is determined by LE.