The HeartbeatMaxServers directive specifies the
maximum number of servers that will be sending requests to this monitor
server. It is used to control the size of the shared memory allocated
to store the heartbeat info when mod_slotmem_shm is in use.
For using flat-file storage (without loading mod_slotmem_shm),
this must be set to 0. The value must be either 0, or bigger or equals 10.