largeHeap=true manifest tag not working?

I´m developing a very memory-consuming app and want to use the largeHeap-Tag, which should give the application a bit more memory. Whatever I set this tag in AndroidManifest.xml to, it makes no difference to the actual memory I´ve been given. I´m reading out my max memory like this:

Log.v("Utils","Max Mem in MB:"+(Runtime.getRuntime().maxMemory()/1024/1024));

My manifest looks quite like this:

<application android:label="@开发者_JAVA百科string/app_name" android:hardwareAccelerated="true" android:largeHeap="true" android:debuggable="true">

    <activity android:name=".EntryActivity" android:label="@string/app_name">
        <intent-filter>
            <action android:name="android.intent.action.MAIN" />
            <category android:name="android.intent.category.LAUNCHER" />
        </intent-filter>
    </activity>

</application>

I´m running 3.1 in the emulator, output of my logging above is always 48MB. Can somebody help?

Use ActivityManager.getMemoryClass() and ActivityManager.getLargeMemoryClass() to verify the approximated values assigned to your app.

Indeed, the large heap will be the same as normal heap until your app needs more memory for a task. Your VM will display such messages on console:

06-30 15:38:14.770: INFO/dalvikvm-heap(9075): Grow heap (frag case) to 42.365MB for 6152016-byte allocation
06-30 15:38:16.680: INFO/dalvikvm-heap(9075): Grow heap (frag case) to 39.739MB for 3517456-byte allocation