In the launch4j configuration for my Java application I have set values for the min. and max. heap size. This works fine, however, for some users it makes sense to override these parameters with other values. Is it possible with launch4j to have "default" settings for the min. and max. heap size, but still allow the user to override these settings via command line parameters?
This is not possible, you can however use an .ini file instead and specify the heap size there. Although the percent of free memory option will not be available, just the regular java options. It's described in the documentation (Additional JVM options at runtime).