Checking for IUI ISPLLIB LIBDEF Support

If you create a REXX or CLIST to invoke the IUI using LIBDEF ISPLLIB, you should check that load module DGADR14 exists in the LIBDEF ISPLLIB library before doing the SELECT PGM. If it does not exist, LIBDEF ISPLLIB is not supported. An example of how to do this using REXX is as follows:
if sysdsn(’$CD.SDGALINK(DGADR14)')  \= "OK" then do
  say “LIBDEF ISPLLIB is not supported by this CD release.”
  say “The CD load module library must be allocated to DD ISPLLIB using ALLOCATE outside ISPF."
  exit 4