Limit on number of database that slapd can open?

["Armbrust, Daniel C." <Armbrust.Daniel@mayo.edu>]

Is there any limit on the number of databases that a slapd server can host?

I have several databases configured to start under one server (all with a bdb backend), and now I get this error on startup:

.....
bdb_db_open: service=ISOTerminologyService,dc=ISO,dc=org
bdb_db_open: dbenv_open(/home/ldap/database/dbisoBDB/)
bdb_db_open: service=ICD9Service,dc=HL7,dc=org
bdb_db_open: dbenv_open(/home/ldap/database/dbicd9BDB/)
bdb(service=ICD9Service,dc=HL7,dc=org): mmap: Cannot allocate memory
bdb_db_open: dbenv_open failed: Cannot allocate memory (12)
backend_startup: bi_db_open(6) failed! (12)
slapd shutdown: initiated
.....

If I removed one of the larger databases, then things work fine.

If I have multiple bdb databases, do each of their DB_CONFIG files need to be the same?  My assumption is that each database gets a cache according to its DB_CONFIG file (or other defaults if it doesn't exist).

Or maybe I running into some system limitation?

I'm using 2.2.5 with the 4.2.52 of Berkeley db if it matters for this issue.

Thanks, 

Dan