Function encode_payloads_memory 

pub fn encode_payloads_memory(
    schema: &Schema,
    payload: &StructArray,
    encoding: PayloadEncoding,
    max_bytes: NonZero<usize>,
) -> Result<usize, Error>

Bounds the owned row-vector allocation before encoding Arrow payloads.

Includes the outer Vec, its row slots and each exact encoded row capacity. Counting borrows Arrow values and uses only bounded stack scratch. The same schema/encoding validation and cumulative max_bytes limit apply as encoding. This does not include consumer codec decoding or its projected DTO allocations.