If you say the server has 16 GB of physical memory, all is not allocated to Qlikview server. The memory can be occupied by operating system and other application's thread if running. So you need to check how much physical memory is available before starting Qlikview server processes and then check how much is left after starting Qlikview server.
It should have sufficient enough to expand your 950MB app in memory + all additional user are allocated separate memory to use application.
Hope this helps,