[Improvement]: SERVER_MEMORY variable in Startup Command

[ssnake]

Expected Behaviour

java -Xmx{{SERVER_MEMORY}} server.jar should not lead to out of memory

Final Outcome

If I start server with {{SERVER_MEMORY}} and server get to max memory consumption OS kills the process because out of memory

Steps to Reproduce Issue

Start any MC server with following command

java -Xms128M -Xmx{{SERVER_MEMORY}}M server.jar

If MC server riches max memory consumption specified in {{SERVER_MEMORY}} OS kills the process.
For example my server has 8GB ram and I want to utilize exactly 8GB, but seems 8GB is used for whole hosting ( OS + java). So as workaround I have to specify -Xmx7800M. This is not convenient and I want to use something like Xmx{{REAL_SERVER_MEMORY}}