From this most recent post, the problem is between your code and your jcl. The error appears to happen before the code even begins to execute. What is in the SYSPRINT after the source you posted? What info (after the source) was printed by Easytrieve?
As i mentioned earlier, i am able to use your file definition and PUT successfullt into the file.
//FILENM DD DSN=&&MYNM,
// UNIT=SYSDA,
// SPACE=(TRK,(1,10),RLSE),
// DCB=(RECFM=FB,LRECL=27,BLKSIZE=2700),
// DISP=(,PASS)
// UNIT=SYSDA,
// SPACE=(TRK,(1,10),RLSE),
// DCB=(RECFM=FB,LRECL=27,BLKSIZE=2700),
// DISP=(,PASS)
I suspect that what you have posted is not complete or has somehow been changed from what you are running on your system.