is there an upper limit of the size tier of stcs?

[Jinhua Luo]

is there a largest tier where the sstables stop merging anymore? if so,
then does it mean some tombstones at that last tier would not be removed?
if not, then it's hard to imagine to compact sstables in huge size, like
10gb; after all, the total size of sstables would definitelly grow, so a
huge sstable would be very likely possible, especially when the range of
the keys is wide.