As per my manual:
Segment translation exception: a program that was running
disabled for interrupts tried to reference storage while
the page table for that storage was paged out. To correct
the error, page-fix the storage before a program running
disabled attempts to reference it.
Another possible cause is that a program tried to
reference storage that had not been obtained. To correct
the error, allocate the storage before attempting to
Finally, a program running in a subspace attempted to
reference storage that was not accessible to the subspace
at the time of error. To correct the error, ensure that
the program running in a subspace references only the
storage assigned to that subspace, or storage that can be
referenced by all subspaces.
In brief check the AMODE and DATAMODE for the program.