Hello sap basis,
many thanks. No, I do not see, which profile the gateway use, but since according to the trace gateway is searching for reginfo file in /usr/sap/P11/ASCS75/data directory, the gateway is really configured to run in ASCS. Probably this is a setup as described in the note 1010990?
1010990 - Configuring a Standalone Gateway in an HA ASCS instance
You have only 2 possibilities to increase the trace level of the gateway - either by setting of parameter rdisp/TRACE=2 in the profile, which gateway is using. If your setup is as per note above, this should be the ASCS instance profile and this parameter will increase trace level also for all other processes of the ASCS instance and a restart is required. Or you can send "kill -USR2 <pid>" on OS level at runtime only to the gateway process.
Since you have mentioned you need to trace everything incoming in message server gateway trace will not be helpful here, because gateway does not communicate with the message server.
Regards,
Alwina