Am Docs recommend Tuning of LDAP Data Store Settings:
To change LDAP data store settings, navigate to Realms > Realm Name > Identity Stores > Identity Store Name in the AM console. Each store has its own connection pool and therefore each store needs its own tuning:
LDAP Identity Store Settings
|LDAP Connection Pool Minimum Size||1||The minimum LDAP connection pool size; a good tuning value for this property is 10.
|LDAP Connection Pool Maximum Size||10||The maximum LDAP connection pool size; a high tuning value for this property is 65, though you might well be able to reduce this for your deployment. Ensure your LDAP server can cope with the maximum number of clients across all the AM servers.
However in the XUI the value of LDAP Connection Pool Minimum Size is missing, as this value is recommended for connection pool tuning it should still be there.
Realms > Realm Name > Identity Stores > Identity Store Name in the AM console