How to know GPU memory allocation is not possible

We are using Intel media sdk32 bit for GPU mode..

Once the memory is  fully utilized , how we can effectively go to CPU mode. We observed that, once the memory is full, CDecodingPipeline.init fails, but init() method  can fail because of lot of reasons.

Any specific way to know GPU allocation is not possible? I mean any specific error code or specific API to see whether GPU allocation is possible or not.