Would you like to try:
data tasks;
set PDBIN;
by JOB;
lenght jx $10; /* max length of job prefix checked */
if _N_ =1 then do i=1 to 578; ctrs(i)=0; end;
if substr(JOB,1,2) in (<list of 2 first characters of JOB names)
then do; jx = substr(JOB,1,2); output; end;
if substr(JOB,1,4) in (<list of 4 first characters of JOB names)
then do; jx = substr(JOB,1,4); output; end;
.....
keep jx job;
run;
proc freq data=tasks;
table jx;
run;