JBoss EAP 7, IO Subsystem workers configurations

What is the main use of the setting for "Io threads" and "Task max threads" under the IO subsystem workers configuration?

Everywhere I read, people are saying that the "Io threads" specify the number of concurrent requests that the server can handle, and that the "Task max threads" is the maximum number of concurrent requests that the server can handle.

So does this mean that if i set the "Io threads" to be 50, that means the JBoss can be handling 50 browser request concurrently?

I have a site where the requirement is to be able to serve 1500 concurrent user within a 15 second time frame. And each request should not take more then 3 seconds to complete. This includes downloading the html, js, css, and all the jpg files that the browser needs.

Does this mean that I need to set the "Io threads" to a higher number, like 100, and the "Task max threads" to 150?

I have tried setting "Task max threads" to 150, and even 250, and it seems to slow down my site.

Anyone can explain how these 2 settings work?