The CERN GKS installation uses logical unit 91 for the dynamic segment storage file. A small file is created on the mini-disk with the largest free writeable space, dynamically extended as necessary, and deleted when GKS is closed. Jobs which crash or fail to call GCLKS will leave the file GKSDYNAM FT91F001 on a mini-disk and it is best to delete it. Applications which create a large number of segments may require up to 5 cylinders of free disk space which can be put on a temporary disk for example.