Default [Q] What is the use of ("ro.HOME_APP_ADJ=1") ?

I wanna know what is the use of this tweak "ro.HOME_APP_ADJ=1" , I am told this will free up more ram because it locks the launcher in memory and use less ram .. but i want to know what exactly this does and will it kill any im messengers running in background like whatsapp?

Ps. I use galaxy y which has only 290mb ram but i have removed and freezed all the bloatware from my sgy so usually my ram usage is 130-150mb with whatsapp and holo launcher running.. will this tweak do any good and will it kill whatsapp? or will i get notifications from whatsapp normally?