Confluence Increase Maximum Heap Size

You can only view Maximum Heap Size  from Confluence > Administration > System Information.

To Edit:

Do not set your memory using CATALINA_OPTS this is overridden by JAVA_OPTS.
On Linux

• In the unpacked Confluence standalone directory, edit the file bin/setenv.sh
• Edit the line beginning with JAVA_OPTS= substituting new values for -Xms (starting memory) and -Xmx (maximum memory)
• Leave the rest of the options in that line unchanged

An example of a minimal setting for a large system - max heap size is set to 1Gb :

JAVA_OPTS="-Xmx1024m $JAVA_OPTS -Djava.awt.headless=true "

Reference