Yep, tool stickout is the distance from the holder to the tip of the tool.

It is importsnt to remember that manufacturers list cutting parameters for "ideal" length of their tools.
It varies from one to another, but normally their stickout is only 2.5 diameters of the cuter.

So a 1/4" endmill should only stick out 5/8" out out of the holder. Such 2 flute carbide endmill can slot aluminum at 0.25" depth of cut.
If longer endmiil is used, depth of cut needs to be reduced by quite a lot.
When you increase length of the cutter twofold, depth of cut needs to be reduced eigthfold if you want to keep the same deflection.
Of cource often you want to sacrafice a little deflection and still run it deeper, thats when you get into trouble.
In order to run deeper, you end up reducing feedrate.
But cutter needs a proper chipload to work efficiently.
In your case you reduced the chipload to the point of rubbing.

So the rule of thumb is: NEVER compensate for extra length by reducing feedate.
Always reduce the depth of cut first.

Also check out my HSMAdvisor. It will help you figure stuff out.