ES 5.0 RC init.d service- which is it doing differently from 2.4?

CentOS Linux release 7.2.1511 (Core)

openjdk version "1.8.0_102"
OpenJDK Runtime Environment (build 1.8.0_102-b14)
OpenJDK 64-Bit Server VM (build 25.102-b14, mixed mode).

ES_HEAP_SIZE is no longer used and I noticed differences in the init.d script between 2.4 and the 5.0 RC.

The 2.4 init.d script has this in it which 5.0 RC does not:

...
start() {
    checkJava
    [ -x $exec ] || exit 5
    if [ -n "$MAX_LOCKED_MEMORY" -a -z "$ES_HEAP_SIZE" ]; then
        echo "MAX_LOCKED_MEMORY is set - ES_HEAP_SIZE must also be set"
        return 7
    fi
...

I'm confused about how its using ES_HEAP_SIZE here.

You have to edit config/jvm.options to set -Xms and -Xmx to another default, or use ES_JAVA_OPTS environment variable.

I know that, but I was just curious what init.d script is actually doing with the vault