Tab(-5,x) sets the number of display rows to x. This was originally only available the AM65 and AM75 terminals, and x was essentially limited to 24 or 42. Under A-Shell, it is still limited to the display device, but in the case of A-Shell/Windows, the display device supports from 1 to 50 rows. In the case of ZTERM, it also supports from 1 to 50 rows. See Selecting a Terminal Emulation.
