Rational Developer for System z
PL/I for Windows, Version 8.0, Programming Guide

Adapting programs using REGIONAL(1) files

You can alter programs using REGIONAL(1) data sets to use workstation VSAM direct data sets. Remove REGIONAL(1) and any other implementation-dependent options from the file declaration and replace them with ENV(ORGANIZATION(RELATIVE)). You should also remove any checking for deleted records, because workstation VSAM deleted records are not accessible to you.

Rational Developer for System z
PL/I for Windows, Version 8.0, Programming Guide