Defining the level of RNR support

RNR support can be defined at three levels: the system level, the terminal level, and the session level.

To use all three levels of control over RNR support, you must:

  • Update the IMS execution parameters to activate RNR.
  • Update the appropriate IMS ETO Logon descriptors for dynamic terminal support.
  • Update the DFSLGNX0 Logon exit support for dynamic override of the RNR option on a session by session basis.

To activate RNR at the system (and default) level, you must specify in the DFSDCxxx IMS.PROCLIB member whether to activate RNR by indicating either RNR=ARNR (Activate RNR) or RNR=NRNR (No RNR).

Using the PSTIMER parameter in the DFSDCxxx IMS.PROCLIB member, you can also specify the maximum time for session persistence following an IMS or VTAM® failure. PSTIMER can be set from 1 to 86400 seconds. The default setting is 3600 (1 hour). If 0 is indicated, then no timer is used and session persistence continues indefinitely.

Note: If the VTAM START option for MNPS, HPRPST, is set to a lower value than PSTIMER, it overrides the PSTIMER setting.

To control RNR support for ETO dynamic terminals, use the OPTIONS= ARNR|NRNR parameter in the ETO logon descriptor. The RNR support specified at this level overrides that set at the system level using IMS execution parameters.

To control RNR support on a session by session basis, use the LGOPT=LGOARNR|LGONRNR parameter for the Logon exit routine (DFSLGNX0). The RNR support specified at this level overrides that set using the ETO logon descriptor or the system level execution parameters.

The parameters of DFSLGNX0 are documented in its source code.