A data transfer system uses a data buffer and individual control of each storage location within the data buffer for improved control of data block transfers. The storage locations are assigned deallocate, active, or valid assignment bands to enable transfer control of the data blocks within the system. The deallocated storage locations are returned to an allocation pool for use as a future resource, where the active and valid assignment bands remain unavailable until deallocated. Error checking and depth control prohibit consecutive allocation or deallocation assignments as well as overflow.