Standard folder location for runtime created application files for MAC/Linux to access

Where should I create the folders/files that the java application I'm developing needs to interact with? Is there a standard place or at least a place that makes the most sense? I was thinking the ${home} or usr/local/share or user/share/ directories perhaps, but there may be a better place.

For example suppose my application needs to create a ftp outbound folder to write csv files to.

Ideally, the folder that it creates should have the following characteristics:

1. It should exist on both Mac and Linux, (as a bonus, Windows would be nice too)
2. It should be referenceable by a common env variable
3. It should not be visible to the common user so that they cannot tamper with it
4. It should be have read/write permissions by default, without needing to chmod or chown it.
5. The file should remain untouched after multiple deployents

Is there such a folder?