This read-write integer (40-100) sets the number of OS buffers the Frame Relay software layer can send through an upper SAP toward GFF before it must receive an acknowledgement, functioning as a flow-control window. Admins tune it to balance throughput against buffer exhaustion on the FRM-to-GFF traffic path. For example, the default window width of 40 buffers is the value applied unless an administrator raises it toward the 100 maximum for higher-throughput links.