The part of my elasticsearch startup script that shows the jvm environment variables I'm using.

gistfile1.txt

# Directory where the ElasticSearch binary distribution resides
ES_HOME=/usr/share/$NAME

# Heap Size (defaults to 256m min, 1g max)
ES_HEAP_SIZE=6g

# Heap new generation
#ES_HEAP_NEWSIZE=

# max direct memory
#ES_DIRECT_SIZE=

# Additional Java OPTS
#ES_JAVA_OPTS=

# Maximum number of open files
MAX_OPEN_FILES=65535

# Maximum amount of locked memory
#MAX_LOCKED_MEMORY=

# ElasticSearch log directory
LOG_DIR=/var/log/$NAME

# ElasticSearch data directory
DATA_DIR=/var/lib/$NAME

# ElasticSearch work directory
WORK_DIR=/tmp/$NAME

# ElasticSearch configuration directory
CONF_DIR=/etc/$NAME

# ElasticSearch configuration file (elasticsearch.yml)
CONF_FILE=$CONF_DIR/elasticsearch.yml