[Haskell-cafe] A guess on stack-overflows - thunks build-up and tail recursion

Hi all, I've been running into stack-overflow problems for some time now. Here is what I gathered so far. I used to think that the build up of thunks caused the stack overflow when, as it turns out, it does not. I apparently can have a huge thunk build up eventhough I use a supposedly accumulative, tail-recursive algorithm. Apparently it is the evaluation of this huge build-up that causes the stack-overflow but not the thunk-build-up *as such*. Do I understand this correctly? Günther