THREADED_EXECUTION specifies whether to enable the multithreaded Oracle model. Starting in Oracle Database 12c, the multithreaded Oracle model enables Oracle processes on UNIX and Linux to run as operating system threads in separate address spaces.
The choice of threading model is dictated by the THREADED_EXECUTION initialization parameter.
THREADED_EXECUTION=NO : The default value causes Oracle to run using the multiprocess model. THREADED_EXECUTION=YES : Oracle runs with the multithreaded model.