Navigate to $IDASH_HOME/bin and open the idash_server file for editing.
Find the JAVA_OPTS line and modify the values for the parameters -Xms which is minimum java heap allowed for the jvm and -Xmx which is maximum java heap allowed for the jvm.
Save the file.
Restart the iDash server using the idash_server stop and idash_server start commands.
1. These values are by default in megabytes (hence the m at the end of the value).
2. There can be no spaces between the parameter and the value.