Applies only to X25 lines. Specifies the maximum size in bytes of the
 frame for the line. This value must be at least 5 bytes larger than
 the maximum packet size you specify in  SET CIRCUIT (for PVCs and
 DLM circuits) or SET MODULE X25-PROTOCOL (for SVCs). Specify a value
 in the range 21 to 4103.

 By default the size of the frame takes the value specified by the
 PROFILE parameter of the SET MODULE X25-PROTOCOL command.