@Sophiechka You can use G92 to set any position, it doesn't have to be X0 Y0 Z0. But you need to know the position of the nozzle to set it.
Usually at the end of gcode jobs, the nozzle is moved away from the print, motors are turned off with M18 and axis position is lost, so the machine needs to be homed. You can change this behaviour if you need to, so the motors keep their position, by removing M18 from the end gcode. Then the axes will not need to be homed, though make sure G28 is not in the start gcode of the next gcode file.
If the second gcode file has been sliced starting at Z0, but you want to print on top of the existing print, send G92 Z0 to reset the Z position at the height of the first print. There may be a move at the end of the first gcode file to lift the nozzle, which you will need to take into account.
If you still want to turn the motors off after each job, you can 'park' the extruder at a known point at the end of the first gcode file, eg X100 Y100 Z100, though make sure it isn't in the way of the print. Then when you want to print the next shape on top (assuming the gcode for this starts at Z0, and the nozzle hasn't moved), send G92 X100 Y100 Z100 to set the current position. Note that when energised, stepper motors move to the closest full step, so it is possible there will be a small change in the position. You will still need to move the nozzle to the Z height of the first print, then send G92 Z0 so the second print can start on top.
Ian
