Check out details of internal / undocumented options with the following code:

proc options internal;
run;

NOTE: Internal SAS system options facilitate testing, development and problem diagnosis of SAS. Internal options are not documented or supported. Customer use of internal options is not recommended, unless specifically directed by SAS Technical Support.

Example output:

Screen_Shot_2018-07-16_at_12.39.03.png

source: Phil Mason (http://www2.sas.com/proceedings/sugi26/p020-26.pdf)