Both DFSORT and ICETOOL can be called from REXX. The key is to specify ALLOCATE statements for the data sets you need and then use an ADDRESS statement like this:

  ADDRESS LINKMVS name

which says to fetch the named program using the standard system search list.

Here is an example of a REXX CLIST to call DFSORT:

/* Simple REXX CLIST to call DFSORT */
  "FREE FI(SYSOUT SORTIN SORTOUT SYSIN)"
  "ALLOC FI(SYSOUT)   DA(*)"
  "ALLOC FI(SORTIN)   DA('Y897797.INS1') REUSE"
  "ALLOC FI(SORTOUT)  DA('Y897797.OUTS1') REUSE"
  "ALLOC FI(SYSIN)    DA('Y897797.SORT.STMTS') SHR REUSE"
  ADDRESS LINKMVS ICEMAN

Here are the DFSORT control statements that might appear in the Y897797.SORT.STMTS data set:

  SORT FIELDS=(5,4,CH,A)
  INCLUDE COND=(21,3,SS,EQ,C'L92,J82,M72')

Here is an example of a REXX CLIST to call ICETOOL:

/* Simple REXX CLIST to call ICETOOL */
  "FREE FI(TOOLMSG DFSMSG VLR LENDIST TOOLIN)"
  "ALLOC FI(TOOLMSG)   DA(*)"
  "ALLOC FI(DFSMSG)   DUMMY"
  "ALLOC FI(VLR)   DA('Y897797.VARIN') REUSE"
  "ALLOC FI(LENDIST)   DA(*)"
  "ALLOC FI(TOOLIN)    DA('Y897797.TOOLIN.STMTS') SHR REUSE"
  ADDRESS LINKMVS ICETOOL

Here are the ICETOOL statements that might appear in the Y897797.TOOLIN.STMTS data set:

 OCCURS FROM(VLR) LIST(LENDIST) -
   TITLE('LENGTH DISTRIBUTION REPORT') BLANK -
   HEADER('LENGTH')  HEADER('NUMBER OF RECORDS') -
   ON(VLEN)          ON(VALCNT)