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*   CE801.??? DB-EZTest Tech Note                          May 1998 *

*                                                                   *

*   KEYWORDS: DB-EZTest   DB2KSET   SVCIN   SVCOUT                  *

*                                                                   *

*   Users may sometimes experience confusing behavior from DB2KSET  *

*             when installing or de-installing the SVC Hook         *

*             mechanism.                                            *

*                                                                   *

*             This may be due to the fact that another 3rd party    *

*             SVC hook mechanism is also in use at your site.       *

*                                                                   *

*             Release 5.2 of EZTest has been changed to disallow    *

*             nesting of SVC Hooks, that is, we will not Hook an    *

*             SVC that is already hooked.                           *

*                                                                   *

*             On SVCIN, we check that the SVCTABLE entry for SVC11  *

*             points to IGC0001A (The real MVS TIME SVC).           *

*             If it does not, then DB2KSET ends with a RC=4 message *

*             "DB905721 EZ2000: TIME SVC HOOK ALREADY INSTALLED".   *

*             This may mean that you have previously installed the  *

*             EZTest SVC Hook. It may also mean that another        *

*             3rd party SVC Hook mechanism has been installed.      *

*                                                                   *

*             On SVCOUT, we check that the SVCTABLE entry for SVC11 *

*             points to DB2KSV2 (The EZTest Hook module).           *

*             If it does not, then DB2KSET ends with a RC=4 message *

*             "DB905721 EZ2000: TIME SVC HOOK NOT INSTALLED".       *

*             This may mean that you have not previously installed  *

*             the EZTest SVC Hook (or already de-installed it).     *

*             It may also mean that another 3rd party SVC Hook      *

*             mechanism (which allows nested hooks) has been        *

*             installed after you installed the EZTest Hook.        *

*             The SVCTABLE in this case would point to the other    *

*             3rd party hook module.                                *

*                                                                   *

*             As this illustrates, it is possible that you could    *

*             receive the "not installed" message after an SVCOUT,  *

*             and then receive the "already installed" message      *

*             executing an SVCIN request. In this scenario, you     *

*             would have to de-install the other hook routine before*

*             de-installing the EZTest hook.                        *

*                                                                   *

*             If in doubt, it is possible to verify what the        *

*             current SVCTABLE entry for SVC11 is pointing to by    *

*             performing the following DCMT Display Mem commands:-  *

*                                                                   *

*             DCMT DIS MEM 10                   display <CVT-addr>  *

*             DCMT DIS MEM <CVT-addr>+X'C8'     display <SCVT-addr> *

*             DCMT DIS MEM <SCVT-addr>+X'84'    display <SVCT-addr> *

*             DCMT DIS MEM <SVCT-addr>+X'58'    display <SVC11-addr>*

*             DCMT DIS MEM <SVC11-addr> 256     display SVC11       *

*                                                                   *

*             At offset 8 from the start of the SVC you should see  *

*             the eyecatch, IGC0001A or DB2KSV2.                    *

*                                                                   *

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