Is the maximum stack size for an ingredient 99? And if you get more what happens? Second stack?

The maximum for a stack is very high. (It's waaaay over http://www.youtube.com/watch?v=SiMHTK15Pik)
Since one piece of gold is counted as one single item, (and we've all had millions of dollars before) all items can stack to a very high amount.

I'm sure there is a limit, but it would probably be 10 digits long. Nothing you ever have to worry about in a normal playthrough.


I think the only items that don't stack are weapons/armor that are damaged (they need to be repaired in order to stack) and items with scripts attached to them.