IBM Support

Enterprise COBOL for z/OS 5.1 and PDSE load libraries

White paper


The new IBM Enterprise COBOL for z/OS version 5.1 compiler provides many features, including improved performance over previous COBOL compilers but requires the executables to be in PDSE datasets. If you currently use PDS datasets for load libraries and are interested in COBOL V5, this information will provide you with the guidance you need to migrate to PDSE load libraries to use COBOL V5.


If you are interested in COBOL V5, and you currently run COBOL programs out of PDS load libraries, then start migrating your COBOL load libraries to PDSE datasets as soon as possible.

IBM understands the challenge of migrating from PDS load libraries to PDSE load libraries, and has received other feedback about COBOL for z/OS V5 and its requirement for PDSE load libraries. 

IBM has investigated the possibility of changing COBOL V5 to support Load Modules and PDS load libraries, however, it is not possible. 

The need for PDSE datasets and Program Objects are built into the very core of COBOL V5.  Just a few examples of features that COBOL V5 uses and will use that require Program Objects(PO) and thus PDSE datasets for executables are:

  • Improved init/term scheme relies on user-defined classes in object, requiring PO
  • QY-con requires PO 
    (A performance improvement for RXY (long displacement) instructions.
  • Condition-sequential RLD support requires PO
    A performance improvement for bootstrap invocation
  • PO can get page mapped 4K at a time for better performance
  • NOLOAD class DWARF debugging data requires PO
  • Common reentrancy model with C/C++ requires PO
  • XPLINK requires PO and will be used for AMODE 64
There are a couple of solutions to the problem of shared PDSE datasets across SYSPLEX boundaries.

One way is to not do Load Library sharing across SYSPLEX boundaries anymore, by using multiple copies of the dataset as PDSE for each SYSPLEX.

If PDS load libraries are shared across SYSPLEX boundaries today, in order to move to PDSE load libraries, you can use a master-copy approach
    • One SYSPLEX can be the writer/owner of master PDSE load library (development SYSPLEX)
    • When PDSE load library is updated, push the new copy out to production SYSPLEX systems with XMIT or FTP
    • The other SYSPLEX systems would then RECEIVE the updated PDSE load library

A more long term solution would be to request from IBM DFSMS and z/OS GRS that IBM extend the capabilities of PDSE datasets to allow them to be shared across SYSPLEX boundaries. 

To do this, please submit a requirement against PDSE and z/OS GRS.

Original publication date


Document information

More support for: Enterprise COBOL for z/OS

Software version: 5.1

Operating system(s): z/OS

Reference #: 7041176

Modified date: 22 January 2014