As far as I'm concerned, an item contained in a view with fit layout, will fit its parent's container.
So I don't think using layout fit and then specifying the second container height to 45% will work. That may work though if you use a fixed height for the second container. But I don't think % will do.
Try another layout for the first container, maybe anchor will work as you expect.
Here's a link to sencha layouts... http://dev.sencha.com/deploy/ext-4.0.0/examples/layout-browser/layout-browser.html
EDIT
Well, this doesn't seem at all like the post you posted before your edit. Try what I suggested for your first code.
It would be best if we used your actual code, but as for this code you posted now... https://fiddle.sencha.com/#fiddle/3hg