Can I extract the user id or user number from the submit message CAVO1112I ?
You can define a VOICE proc that will log the user id doing the SUBMIT into a member.
To be safe, you should define all your users with VOICE=VOICELIB to prevent any user using their own SUB voice proc.
SUBMIT=NO should also be specified for all the users so that they are unable to submit a job outside of the VOICE proc.