Please note that Jaspersoft Community has largely moved away from hosting these older installers directly on their primary "Download Now" pages, prioritizing the latest security-patched releases instead. Download jasperreports-6.6.0.jar (JasperReports Library)
If you cannot locate the official package, consider these last-resort options: download jaspersoft studio 6.6.0
-Xms512m -Xmx2048m