max_payloadafter the connection is made. This will allow the application to chunk or limit data as needed to pass through the server.
max_control_lineoption that can limit the maximum size of a control line. For PING and PONG this doesn't come into play, but for messages that contain subject names and possibly queue group names, the control line length can be important as it effectively limits the possibly combined length. Some clients will try to limit the control line size internally to prevent an error from the server. These clients may or may not allow you to set the size being used, but if they do, the size should be set to match the server configuration.
It is not recommended to set this to a value that is higher than the one of other clients or the nats-server.
This functionality is only used for debugging the client library or the nats-server themselves. By default the server sets it to on, but every client turns it off.