Set the "standard" number of screen rows.

 

TN3270

For TN3270 applications, 24 is recommended for standard rows.

 

TN5250, TNVT

For 5250 and many TNVT connections, this should be 25, to accommodate an additional status line.  For Windows/2000 and Windows/XP TelNet servers, 25 is needed to avoid unnecessary scrolling.