This assumes you have reviewed IBM GSKit (Global Security Kit) - Getting Started.

If you did not use the "-default_cert yes" option when adding a certificate, you can set a certificate as the default certficate using the "-setdefault" option.

ihs_home/gsk8/bin/gsk8capicmd_64
-cert
-setdefault
-db /path/to/example.kdb
-stashed or -pw your_password
-label "certificate_name"

You can list the certificates in the key database to determine which certificate is the default certificate. In this example, the certificate named "example.com" is the default certificate.

Certificates found
* default, - personal, ! trusted, # secret key
* example.com
- bogus.com