Deleting Macro Variables

Each SAS session has a finite amount of memory allocated to for macro variables. Whilst it is usually plenty; there are other good reasons for removing global macro variables when they are done with from your SAS sessions. For example, if many individual programs are included (see the %include statement) then you should avoid the possibility of a value being reused by another program.

The statement %SYMDEL can be used to delete macro variables from the global symbol statement in SAS. Its syntax is:

%SYMDEL variable-name ;

* Create a macro variable via call symputx;
data _null_;
   if 0 then set sashelp.class nobs=nobs;
   call symputx('no_records',nobs);
   stop;
run;

* Create a macro variable via %LET; 
%let my_constant = ABC; 

* Check they exist (see log file); 
%put _user_; 

* Clean up; 
%symdel no_records my_constant; 

* Check they do not exist (see log file); 
%put _user_;