Solution : https://service.sap.com/sap/support/notes/746299 (SAP Service marketplace login required)
Key words : 
'cluster-data'->'instance_idxxxxxxx'->'server_idxxxxxxxxx'-> general-xms2048m           initial heap size -xmx2048m           maximum heap size -xconcurrentbackground1           controls, -xms200m                     initial heap size            -xmx200m                     maximum heap size -verbose, -xmx1024m            maximum heap size            'cluster-data'->'instance_idxxxxxxx'->'dispatcher_idxxxxxxxxx'-> 'general', application            'cluster-data'->'instance_idxxxxxxx'->'message server & bootstrap', lang=en_us&source=swg-ibmjavaisvthe access key, running'<jdk path>/jre/bin/java -fullversion', soft references            survive -xconmeter2           instructive parameter, shorten gc pause times -xconcurrentlevel6           controls, starting concurrent gc work -xsoftrefthreshold0           controls, ibm j9 technology general availability
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