Have you had a look at page 53 of the manual?
The NetBackup for DB2 configuration file, db2.conf, consists of a series of keywords and values. This file defines how to back up the database and the archive logs. It must be created on each NetBackup for DB2 client.
The installation package installed a file named db2.conf that you can customize. The following procedures show you how to customize this file.
Follow the instructions in this section if you use the user exit program to perform backups.
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Copy the sample db2.conf file from its location in the sample directory to its active location.
Its location in the sample directory is as follows:
/usr/openv/netbackup/ext/db_ext/db2/scripts
The active location for the db2.conf file is as follows:
$DB2_Instance_Home/db2.conf
In the db2.conf file, create an object identifier for backing up the database.
This object identifier starts with the following keyword lines...........