Android memory management question

I have bunch of queries regarding android memory management . I know each app is provided with jvm , but how about memory size , do they increase and decrease with respect to other apps on phone?

The main part how do jni memory allocation in each jvm taken care ?

When accessing one of the android default native methods , where does memory allocation take place?

开发者_开发百科Can low memory cause segmentation faults , when native methods are executed ?

Considering the scenario i am trying to test , where there is low memory for my app and native calls can cause issue.What are effective ways to test low memory scenarios on android

Thank you

I guess java jni memory management would apply for android too. I found the below link useful to understand for memory allocation http://www.slideshare.net/gengmao/inside-the-jvm-memory-management-and-troubleshooting