Y siguiendo con las limitaciones:
Cita: post_max_size integer
Sets max size of post data allowed. This setting also affects file upload. To upload large files, this value must be larger than upload_max_filesize.
If memory limit is enabled by your configure script, memory_limit also affects file uploading. Generally speaking, memory_limit should be larger than post_max_size.
(se refieren a configuración de PHP en su php.ini)
Un saludo,