IBM TSO/E Logon terminal Website→

It might not be a web site, but that does not make it less bad. Since many don't know about IBM mainframes, it seems they don't think you need to up the policies.

Default old password policy is: 6-8 characters long, A-Z, 0-9

Over the last few years they have updated their policies a bit, but due to many of their subsystems are incompatible, they can't enforce the new options for safer passwords.