You only need a LAMP stack when you want to present a web server.
If you are wanting to run a number of virtual servers via OpenVZ on a single hardware server, you should not install the LAMP components on the host OS. Install them on the guest OS's if you need them.
On the other hand, you may wish to have some management and reporting via the host OS, in which case, there may be a need for a web server to be running, check the requirements for the management and reporting tools.