src/sys/stash/meta/stash2.cmx

{
    "program": {
        "args": [
            "--secondary_store",
            "--backing_file",
            "/data/stash2.store"
        ],
        "binary": "bin/app"
    },
    "sandbox": {
        "features": [
            "isolated-persistent-storage"
        ],
        "services": [
            "fuchsia.logger.LogSink"
        ]
    }
}