A quick workaround to keep the screen session alive is easy. Just start a second shell (with
c and start a program.
According to this page it is possible to set read only variables in csh and tcsh with
set -r. Quoting from that page:
Variables may be made read-only with `set -r' (q.v.) Read-only variables may
not be modified or unset; attempting to do so will cause an error. Once made
read-only, a variable cannot be made writable, so `set -r' should be used
with caution. Environment variables cannot be made read-only.
Which means you can not unset or change this in this shell.
This seems to leave you a few options:
For starters you can check your homedir for a
.login or a
.cshrc If they are set in either of those two, edit the file and it will be active when you log in next.
Alternatively it can be set from
/etc/csh.cshrc in which case it is a default for all csh users on the system. I am not sure if you can override that by setting another value in your own config files. That probably comes down to which configuration file is read first.
Thirdly you can compile your own csh. This is probably a bit over the top, but if you need csh then it is an option.
Lastly: If you do not need cch but just a shell you could check if other shells (ksh, bash, /bin/sh) are configured with the same values. It feels like a dirty workaround (even worse than compiling your own version) so I left this as last option.