In a program-
If it contains ORGANIZATION IS INDEXED then it is using KSDS.
If it contains ORGANIZATION IS RELATIVE then it is using RRDS.
If SELECT clause contains ASSIGN TO AS-xxxxxxxx then ESDS.
Now to find which VSAM-
search for program name in your PROCLIB and JCLLIB.
Read the procedure for the DDNAME you got from the program. ( Remember 'assign to xxxxxxxx' will be DDNAME used in JCL )
Please let us know if I missed something or interpreted your question wrongly