This article describes possible reasons for 'HostingEnvironment initiated shutdown' message that might sometimes appear in Event Log.
This is caused by your hosting provider restarts/shutdown the application for some reason. Some hosting providers are restarting application e.g. if it exceeds some memory, or CPU time limit. Try eventually to ask your hosting provider under which circumstances they restart/shutdown the application.
Please see the following knowledge base article for more details support.microsoft.com/kb/920970/
.See also: Recompilation limit of 100 reached
More on this also in blog post