I don't know the right heap size for this , but the following below did help me.
-Xms64m -Xmx1G -XX:MetaspaceSize=2G -XX:MaxMetaspaceSize=2G -Djava.net.preferIPv4Stack=true
Also for me even after setting in the standalone.conf the value wasn't reading. Make sure the initial part of the log prints the value you gave and not the previous one. For me I had to set an environment variable of name JAVA_OPTS with above value for it to really work. If you look the standalone.conf it is written to read the environment variable first and if not available then from configuration.
But if you just had to make some POCs for testing or working on local you could use the docker image available.If you use a showcase image it already comes with prebuilt users and role and needs no configuration to run. Up the kie workbench and kie server with following commands.
docker run -p 8080:8080 -p 8001:8001 -d --name drools-wb jboss/drools-workbench-showcase:latest
docker run -p 8180:8080 -d --name kie-server --link drools-wb:kie-wb jboss/kie-server-showcase:latest
if the business central gets slow while running on containers increase the resource allocation for docker.
Hope it helps.
Best Regards,
Vishnu Chalil
Associate Engineer
INDIA | USA | UK | ISRAEL