DISCONNECT command for the UNIX system

[Andrei V. Zaitsev]

Some computer systems (like VMS or VM/CMS) have the DISCONNECT
command. This command sometimes more convinient then LOGOFF,
bacause it saves all the terminal and environment characteristics
and you can re-login really quickly.
Have anybody heard about the software which implements this 
command for UNIX ?
Or , maybe , anybody have ideas how to create such a program ?