I've seen this error previously when someone is executing batches which contains more than 64K statements which is beyond the limit.
I have to admit that I'm struggling to understand a valid use case beyond 10s of statements in a batch, let alone hundreds or thousands. If you do have very large batches, I'd like to point out that batches are not an optimisation in the same manner as they are in RDBMS.
This is however a little contrary to your description that you're setting read consistency so perhaps there's some wires crossed here. In any case, SERIAL and LOCAL_SERIAL consistencies are only valid for the read phase in the read-before-write of lightweight transactions so they're not valid for regular reads. Cheers!
[EDIT] If you provide a bit code that replicates the issue, I'd be happy to review it and figure out the underlying issue. Cheers!