Kerberos ticket is deleted when running vastool kinit with su
What is happening is that once you log out your cache is destroyed and therefore once the su - finishes so does the cache
Set no-cred-cleanup = true
no-cred-cleanup = <true | false>
Default value: false
By setting the no-cred-cleanup option you are telling QAS to never attempt to cleanup credential caches at all. The side effect of this would be a build up of expired
or otherwise useless credential caches in your /tmp directory. The automatic ticket renewal feature of QAS will dispose of such credential caches when it runs (every
few hours). If you wish to dispose of these caches earlier you may also run the vastool flush ccaches command. See the vastool man page for further details.