comment-use-global-state is a variable defined in `newcomment.el'.
Its value is

Non-nil means that the global syntactic context is used.
More specifically, it means that `syntax-ppss' is used to find out whether
point is within a string or not. Major modes whose syntax is not faithfully
described by the syntax-tables (or where `font-lock-syntax-table' is radically
different from the main syntax table) can set this to nil,
then `syntax-ppss' cache won't be used in comment-related routines.