Cyrus DB Error -- Logging region out of memory

[Proskurin Kirill]

Hello again.

Today im found this error at logs:
imaps[48731]: DBERROR db4: Logging region out of memory; you may need to 
increase its size
imaps[48731]: DBERROR: opening /var/imap/tls_sessions.db: Cannot 
allocate memory
imaps[48731]: DBERROR: opening /var/imap/tls_sessions.db: cyrusdb error
imaps[48731]: DBERROR: opening /var/imap/deliver.db: cyrusdb error

And so on.
After googling im found what it may be fixed by a increase "Log region 
size" parameter at cyrus db.

It is the only way? And how much it must be increased?

My system:
FreeBSD 6.1-RELEASE-p10
cyrus-imapd-2.3.7
cyrus-sasl-2.1.22
cyrus-sasl-saslauthd-2.1.22

-- 
Best regards,
	Proskurin Kirill