The SETPRT macro automatically positions forms in the printer to the first line of a new page when a new FCB is requested. If you wish to position the form yourself, specify the N option of the FCB parameter and insert the new form, matching the top of its page to the same position as the old form occupied.
This is how the SETPRT macro aligns a new form: If the FCB is different from the one currently in the printer, the old FCB and its current position is read from the printer. If the old form is not already at the top of a page, a temporary FCB is constructed and loaded back into the printer. A skip to 1 command is then executed to move the old form to the top of a new page. The requested FCB is then loaded into the printer. SETPRT's preparation is now complete. The new FCB and the old form are now at the first line of a new page. Printing is ready to start. If you wish to bypass automatic forms positioning, use the N option of the FCB parameter.