Hoping some 'ol Ags can help me out here. What the heck was a "stack accountant"?

I stumbled across the 1940 Census and found out my grandfather was a "Stack Accountant" in 1940 for an oil producing company in Houston. He died young, my grandmother has also obviously passed, my mom passed in 2015, and all her siblings have passed, so I cannot ask any of them. I am certain the Census says "stack accountant"; the handwriting is legible and letters are consistent with other easily recognizable words. Internet searches turned up nothing that made sense (there's IT "stacks", but they didn't have computers then).

I'm a CPA who has spent his career in energy in Houston, so it was fun to find this little nugget. Hoping someone can solve what the heck a "stack accountant" was. Again, I am certain the Census record wasn't actually "staff accountant", since it was clearly legible.

Many thanks! I think you probably solved that the word is likely "stock", not "stack". I looked at it again and it looks like all over the page whoever the Census taker was wrote their cursive "a" and "o" very similar. I got locked onto whether it was "staff" that I didn't see the more obvious (simply it's an "o", not an "a").