I think "strict" would be more in line with other uses in code. There are currently no other occurrences of 'strictmode' in the code. There are loads of references to 'strict', but I didn't go through all of them to see if any were used as externally visible function parameter names.
I am sorry, I don't understand to this point. You unlike the name of parameter "strictmode" ? Have you any proposal? Maybe "restrictive" ?