Use jvm.options or ES_JAVA_OPTS to configure the JVM ES_HEAP_SIZE=16G: set -Xms16G and -Xmx16G in jvm.options or add "-Xms16G -Xmx16G" to ES_JAVA_OPTS

Elastic Stack Elasticsearch
4

Can you try:

ES_JAVA_OPTS="-Xms16G -Xmx16G" ./bin/elasticsearch