landscape format in spool converted to pdf
I've created a pdf from a spool job and I was wondering about changing the page orientation to landscape. I want to change it from the function GET_PRINT_PARAMETERS or the function CONVERT_ABAPSPOOLJOB_2_PDF but I haven't found anything related to portrait or landscape orientations. I don't know if it's automatically set by specifying the line size parameter or it has to be put in some of these two functions or in the pdf generation (I'm creating it by using the method add attachment from a cl_document_bcs object).
Does anybody know how can I get this?