# hooks-field-add-buf-len

Emplacing a new field into STObject by calling [sto_emplace](https://xrpl-hooks.readme.io/v2.0/reference/sto_emplace) requires enough space to serialize the new STObject into; the API also limits sizes of the old object and field.

This check warns about insufficient output buffer space as well as too-large values of the inputs in calls to `sto_emplace` (if they're specified by constants - variable parameters are ignored).

[Read more](https://xrpl-hooks.readme.io/v2.0/docs/serialized-objects)
