For most runnables the ajpNumWorkerThreads parameter and the httpNumWorkerThreads parameter are set. Those values should be monitored.
If they regularly exceed 80% of the configuration parameter of the runnable, it has to be scaled out by adding a new runnable of the same type.
For advanced ARIS server installations Software AG strongly recommends that you request an installation service by Global Consulting Services. You can order that service from your Software AG sales representative.