Is there an alternative to krb5.conf file????

[Ahluwalia, Ish]

Hi All:

Is there an alternative to krb5.conf file to initialize and setup kerberos realm?  I tried to use "krb5_set_default_realm" API call, but it didn't work.  This api call asks for a char* to realm name which I provided for e.g. "REALM.COM".  But some how when I use the API calls "krb5_sname_to_principal" and "krb5_unparse_name", kerberos prints a service name "service/nj.domain.com at domain.com".  I service name should have been "service/nj.domain.com at REALM.COM".  
Any insight into this will be highly appreciated.  Essentially, I want to get away from setting up any kind kerberos configuration file for realm setup and want to do it through Kerberos API in an automated way.

Thanks.

Ish...