It's not that those libraries "not allocate" but they work with stack allocation / provided buffers. You can reuse the provided buffers / output objects ... But

It's not that those libraries "not allocate" but they work with stack allocation / provided buffers. You can reuse the provided buffers / output objects ... But a lot of req/resp code doesn't so it's just pushing the cost higher up the stack (app vs libraries). Which it self is a good argument for "transactional" GC.