You can find it in the documentation included in the CY4611 reference design materials located here.You can also refer the following application note FX2 GPIF Flow State Feature for UDMA.
Usually it unnecessary to implement the flowstate feature in non-UDMA GPIF applications and doing so will probably just add unnecessary complexity to the interface.
One situation that may require using the flowstate feature is when the data is asynchronous and needs to be sampled on both the rising and falling edges of a strobe signal. In this situation, an application specific flag could be tied to the strobe signal and you may want to utilize the flowstate feature of GPIF. Otherwise, a non-flowstate implementation should be sufficient.