Maximum size:[1] There is no maximum size for the Sukkah . [1] Michaber 634:1; Rambam Sukkah 4:1
Maximum size:[1] There is no maximum size for the Sukkah [and hence even if it is 1000×1000 Amos it is Kosher].
[1] Michaber 634:1; Rambam Sukkah 4:1