expand to available height

I’ll bet this have been answered, but . . . . I want to automatically expand my web app the maximum height available, but not full screen . . .

How?

You may want to have a look at http://rubberviews.com/rubberviewswe.html

Can’t purchase a product. Seems like it should be easy to get the screen resolution . . .

Not screen resolution. Browser window size. WebPage size…

so, opening the browser window to max height automatically can’t be done?

There is a fullScreen API somewhat implemented in the very latest versions of browsers but it fails in all others.
http://www.sitepoint.com/html5-full-screen-api/

The size of the browser window is up to the user, not the code running inside it. As I recall, even with the FullScreen API it requires a user event like a mouse click to make it work.