As one of the core collaboration services, Calendar provides a standards-based method of scheduling tasks and resources.
Like most other services, the data repository for the Calendar service is located at /Library/Server/. Within that directory is a folder containing data specific to the Calendar service at /Library/Server/Calendar and Contacts/.
Within that folder is a Config folder that has the main configuration file, caldavd-system.plist, for the caldav daemon.
Logs are also stored in the /Library/Server/Calendar ...