Configure snapshot controlfile

It is a copy of the actual controlfile and used for RMAN job execution.
When an RMAN job executes, it reads the information from the controlfile. but the controlfile is always updated when there is updates on files such as datafile and redo log files of oracle physical files.
RMAN always takes a snapshot of the controlfile before staring job execution and the actual controlfile will be updated through RMAN once the job is completed.

To configure snapshot controlfile to a specific location other than the default :

RMAN> configure snapshot controlfile name to 'D:\APP\ADMIN\PRODUCT\12.1.0\DBHOME_1\DATABASE\SNCFDBDB2.ORA'

And find the location of snapshot controlfile:

RMAN> show snapshot controlfile name;
 RMAN configuration parameters for database with db_unique_name DBDB2 are:
CONFIGURE SNAPSHOT CONTROLFILE NAME TO 'D:\APP\ADMIN\PRODUCT\12.1.0\DBHOME_1\DATABASE\SNCFDBDB2.ORA'; # default
 RMAN>