you can not configure GG to replicate the entire database as one shot with one parameter, but you can specify table level replication or schema level replication as below,
so if you need to replicate the whole database to need to specify all schemas in the extract parameter file:
-- specific tables
-- specific users with all tables
If you want to replicate you whole date base, maybe you can use DataGuard.
Why do you want to replicate you whole Database ? what kind of replication: Active Replication, One Load, Uni-directional, Bi-directional ?
If you answer that you would find the correct way to implement your database replication.
As pointed out, what do you mean by replicate? The physical copy of the database (Data Guard physical standby), the logical copy (Data Guard logical standby), or schemas/tables (Streams, GoldenGate)? When you perform the replication, is the data supposed to stay synched? Is there a failover requirement?
In OGG 11.2.1 you can add _ALLOWWILDCARDSCHEMAS into the GLOBALS parameter file, or in OGG 12.1 it's automatic, and then in the EXTRACT and REPLICAT you can use the following syntax:
MAP *.*, TARGET *.*;
p.s. This will automatically exclude internal and system schemas.