Here is a sample code to list out members from a PDS that match your criteria
/*rexx*/
dsn = "MY.PDS"
DUMMY =OUTTRAP("MEMB.","*")
"LISTDS '"dsn"' MEMBERS"
do i = 1 to memb.0
if SUBSTR(strip(memb.i),1,3) = 'LIS' then
say "memeber :" memb.i
end
Hope this helps