Using a separate config file, without disturbing the system's

[Ligesh <myself@xxxxxxxxxx>]

 If you want zsh to parse your custom configuration file in the non-interactive mode, currently it seems, the only way is to add it to .zshenv file. Now I want to start a session with a completely different configuration file and stay in that config file till the end of the session.

 In bash I can do it by specifying --rcfile and then setting the BASH_ENV to the separate file.

 For instance,

 $ bash --rcfile ~/different_bashprofile

 and in the different_bashprofile

 I set, BASH_ENV=~/different_bashrc. 
 
 That way I can work on a system without interfering with the systems configuration at all. I have not been able to do the same on zsh, even though I have searched high and low. Can anyone tell me if such a thing is possible?

 Thanks in advance.