[CentOS] CentOS 6 kickstart missing 'shell command prompt' screen at ALT+F2

Sat Apr 16 00:48:42 UTC 2016
David Copperfield <cao2dan at yahoo.com>

 I've recently setup a centos 6 kickstart environment. Interesting fact is that the helpful 'shell command prompt' screen is missing when I press ALT+F2 key combination even on locally connected keyboard and monitor. ( my kickstart runs in text mode).

All other screens can be found without issues with ALT+Fn key combination. 

I googled internet, and found someone reported similar issues, say, here is one link: http://serverfault.com/questions/322374/kickstart-virtual-console-no-shell-prompt-at-alt-f2.
I read the link several times and still dont quite see why this happens, got confused at the following places:
1, when -- at which installation stage -- the 'shell command' screen will show up?2, if centos 6.6 and 6.7 comes without 'shell command prompt' screen with default installation media, then which installation media contains the file(s) that we can tune? /etc/inittab doesn't contain the entries related to tty consoles.
Centos 7.x doesn't have the issues and it looks like centos 7 leverages a new method to get shell command prompt.
Many thanks in advance.