SQL Server 2012 Crashes and service doesn't restart
You are running into a known bug - There is a fix for it but update to SP2 rather than installing the hotfix.

The errorlog contains SQL Server is terminating a system or background task HADR Task due to errors in starting up the task (setup state 1). and you are using availability groups. The memory leak  is in the MEMORYCLERK_SQLLOGPOOL which is used for transaction log activity.