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zEDC Helps Compress System Management Facility Data

APARs of Interest

There are a couple of APARs that might be of interest if you are planning on messing around with zEDC and zEDC Express. They either fix issues or add functionality, with all three being important to making all this stuff work successfully. Helpful APARs include:


    This APAR supplies decompression services compatible with z/OS authorized interface for zEDC Express (copied from APAR cover). APAR OA41245 closed July 26, 2013, and superseding PTFs (UA70070, UA70072 or UA70071) are available for multiple versions of IOS Extension (5752SCIQP). This APAR is also marked for special handling. There are also lots of excellent details in this APAR’s cover.

  • OA41156: NEW FUNCTION—Tolerate SMF zEDC exploitation and SMFPRMxx keywords

    IFASMFDL, the log stream dump utility, is enhanced to decompress any SMF records read when those records were compressed using zEDC. APAR OA41156 closed Aug. 1, 2013, and superseding PTFs (UA70162 or UA70163) available for multiple versions of the SMF Scheduler (5752SC100). This APAR is also marked for special handling. This is another case where there is lots of excellent details in this APAR’s cover.

  • OA41817: SMF zEDC exploitation corrections

    Miscellaneous fixes for the zEDC exploitation. APAR OA41817 closed on August 1, 2013 and superseding PTF UA70157 is available for SMF Scheduler (5752SC100). No special handling is required for this APAR.


    Encryption Facility for OpenPGP. A detailed description of the feature is added in the APAR’s PDF file.


    Delivers Extended Format BSAM and QSAM data set compression, adds COMPACTION option to the SMS DATACLAS structure, and adds a COMPRESS option to IGDSMSxx member in PARMLIB.

Refer to the IBM support website for the details on the above APARs here.

Sample Set-up Details

At a minimum, there are three SYS1.PARMLIB members that have to be created and/or updated to get zEDC and zEDC Express functioning.

The first is the SYS1.PARMLIB member IFAPRDxx; it has to modified. There’s a good chance you may already have this member in your SYS1.PARMLIB.

If you have any products that require product enablement—like zEDC—this is the PARMLIB member that has the definitions. Did I mention that zEDC is a for fee addition to z/OS?

Specify the NAME of the product it belongs to (z/OS), the FEATURENAME (in our case that will be ZEDC), the product ID (5650-ZOS), optionally the VERSION, RELEASE, and MOD (all three of these defaults to *), and the most important sub-parameter, STATE. STATE is set to ENABLED, DISABLED and NOTDEFINED.

I used the “z/OS MVS Initialization and Tuning Reference” section on “Parameters for IFAPRDxx” as reference.

Next, a change needs to be made to your SMF parameters in member SMFPRMxx. More than likely you already have this member defined for your system. You’ll just have to add an additional parameter.

To take advantage of zEDC with SMF data, you’ll have to specify the COMPRESS parameter on the SMFPRMxx member in SYS1.PARMLIB. SMFPRMxx controls the behavior of the SMF for your z/OS. You can also specify the option parameter PERMFIX(nnnM) on the COMPRESS parameter. PERMFIX defines the amount of storage that should be fixed for use by zEDC Express. A larger amount of storage increases the performance of SMF but decreases the amount of storage available to other applications. A lower value for PERMFIX improves storage availability but can have a negative impact on zEDC performance.

If the zEDC feature is not available to SMF, SMF data is not compressed and IFA730I message is issued.

I used the “z/OS MVS Initialization and Tuning Reference” section on “Parameters for SMFPRMxx” as reference for the above.

Finally, you’ll have to add member IQPPRMxx, introduced by z/OS v2.1, if this is your first time using zEDC. The IQPPRMxx member, also part of SYS1.PARMLIB, has the parameters that control the use of Peripheral Component Interconnect Express (PCIe) features. In our case that would be zEDC Express. The statement in the IQPPRMxx member used to manage application requests that use zEDC features is “ZEDC”. zEDC Express is the only feature controlled by this member so far.

The three sub-parameters for ZEDC in IQPPRMxx are:

  • MAXSEGMENTS—The number of 16MB storage segments allowed. This value can be increased using the SET IQP command but it cannot be lowered. Its default value is four.
  • DEFMINREQSIZE—The minimum data size that can be compressed by the zEDC feature specified in Kb. Its default size is four or four Kb.
  • INFMINREQSIZE—The minimum data size that can be decompressed by the zEDC feature specified again in Kb. The default value is 16 or 16 Kb.

Once again, the “z/OS MVS Initialization and Tuning Reference” was used. This time, the section on “Statements/parameters for IQPPRMxx” was referenced.

Don’t Be Left Behind

Here's a little off-topic information about z/OS in general. If you missed the announcement, z/OS v1.11 went out of service back on Sept. 30, 2012. However, are you aware that z/OS v1.12 will go out of service on Sept. 30, 2014? More importantly, z/OS 1.13, your migration point into z/OS 2.1, is out of marketing with an out-of-service date of Sept. 30, 2016, giving you a little more than two years to complete your migration to z/OS v2.1. Hopefully you’ll find this information helpful when planning for your release installation.

Willie Favero is currently an IBM Senior Certified IT Software Specialist and the DB2 for z/OS SME for the Data Warehouse on System z Swat Team at IBM's Silicon Valley Lab.

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