The $SetL function sets the current line counter for the output device currently in effect to the value specified as the $SetL argument. Use the $SetL function only when routing output to an external data set. You cannot use $SetL with full-screen devices.
$SetL returns a number representing the maximum physical line length allowed on the current output device. This line length is determined from the OUTMRL and OUTCCC parameters or, if an alternate output device is being used, from the LRECL specification on the USE data set DD statement and the UDDCCC parameter. All parameters are described in the List of Model 204 parameters.
The $SetL function does not ordinarily reposition the output device or perform any input/output operations. It simply alters the value of the line counter for the device. When this counter is compared to the value of OUTLPP or UDDLPP, the effective size is changed for the current page. If the counter is set to a value equal to or greater than the effective lines-per-page value (OUTLPP or UDDLPP), a NEW PAGE action is forced.