well, the standard JCL to execute a REXX program is something like this:
//GO EXEC PGM=IKJEFT01
//SYSTSPRT DD SYSOUT=*
//SYSEXEC DD DISP=SHR,DSN=WJENSEN.LIB.EXEC
//SYSTSIN DD *
where your program is stored as a member in the PDS referenced by the SYSEXEC JCL statement.
The program is normally named in the SYSTSIN JCL statement, though is can also be named by the JCL PARM statement. In this case the program is the member HELLO of the WJENSEN.LIB.EXEC PDS.
You say that you want to pass a PDS to the REXX, but not how you intend to use it. A PDS normally cannot be read by a REXX program, but a member of a PDS can. The JCL statement for allocating your PDS would most likely be
//PDS1 DD DISP=SHR,DSN=REXX.OUTPUT.REPORT
but it depends on the type of usage that you intend.