A method of visual media processing is provided. The method includes determining a size of a buffer to store reference samples for prediction in an intra block copy mode, and performing a conversion between a current video block of visual media data and a bitstream of the current video block. The conversion is performed using the reference samples stored in the buffer, and in the intra block copy (IBC) mode. The IBC mode is based on motion information related to a reconstructed block located in same video region with the current video block without referring to a reference picture.