DB2 user-defined functions (UDFs) and stored procedures can be either fenced or not fenced.
Fenced UDFs and stored procedures run under the fenced user and group and cannot access most DB2 internal control and data areas, whether inadvertently or deliberately. This separation between the data and the stored procedure or function makes fenced UDFs and stored procedures a safer choice for the database.
Not fenced UDFs and stored procedures run in the same address space as the database manager. This results in increased database performance, but user code can accidentally or maliciously damage the database control structures. You should use not fenced stored procedures only when you need to maximize the performance benefits.
For security reasons, it is recommend that you do not use the instance name as the fenced user. However, if you are not planning to use UDFs or stored procedures, you can set the fenced user to the instance name instead of creating another user.
In a Network Information Services (NIS) environment, users and groups are remotely managed from an NIS server. Users and groups that you want to use with DB2 must exist on the NIS server prior to installation. The DB2 Setup wizard cannot create users or groups in an NIS environment.
To create a new user, click New user and provide information about the fenced user in the fields.
The User name you specify must be a valid DB2 user ID.
The Group name you type can be an existing group you have defined, or a new group that will be created if it does not exist. The group must be the primary group of the user.
Type the UID if you want a specific UID to be used. Otherwise, select Use default UID to use a system-generated UID.
Enter the GID if you are creating a new group and you want a specific GID to be used. Select Use default GID to use a system-generated or already-existing GID.
The Password you specify:
The Home directory is used to store information that pertains to the fenced user. You cannot change the location of the directory once it is created. In a partitioned database system, the directory is shared between all partitions belonging to the instance. Therefore, it must be created on an NFS mountable drive that all computers in the instance can access.
The directory can be any valid new or existing directory, although permission problems can arise if an existing directory is used.
Click Existing user to use a user ID that you have created previously.
Click [...] and select an existing User name.
The DB2 Setup wizard will check the user ID, home directory and password for validity. The user ID and password are stored in the operating system security files.