DFSHSBxx member of the IMS PROCLIB data set

Use the DFSHSBxx member of the IMS PROCLIB data set to specify the XRF options used by the active and alternate subsystems in an XRF complex.

Multiple DFSHSBxx members can be present in IMS PROCLIB data set. The HSBMBR= parameter in the IMS procedure identifies the member currently in effect.

An XRF complex has two DFSHSBxx members in effect at any time, one for the active system, and one for the alternate subsystem. The two members need not be identical, but the USERVAR and RSENAME parameters must be the same, and the surveillance options should be the same. If MNPS is used for terminal switching, then the USERVAR parameter is not applicable. Instead, the MNPS parameters must be the same in the two members.

Environments

This member is not applicable in the DBCTL environment.

Syntax

The XRF option parameters can occur in any order in the control statement. Multiple control statements can be provided.

RSENAME= is required for all XRF complexes. Either USERVAR= or MNPS= is required if you use VTAM® for XRF terminal switching.

Restrictions

Usage

The parameters in this member can have different meanings, depending on whether the subsystem is the active or the alternate subsystem.

The record format is:

Position: Contents
1-71: Option parameters separated by commas
72-80: Ignored

The first parameter in a record can have leading blanks. The last parameter in a record is denoted by a comma, followed by one or more blanks. The last parameter in the last record is followed by one or more blanks.

Parameters

ALARM=

Specifies whether (YES) or not (NO) the service processor alarm on the alternate subsystem sounds at takeover request. The default is NO.

AUTO=

Specifies whether (YES) or not (NO) a takeover is to proceed automatically. The default is NO.

DEFERFIX=xx

Identifies the DFSFIXxx member of IMS.PROCLIB containing the non-Fast Path page fixing options for the control region, which are processed during the restart of an active subsystem, and when the alternate subsystem becomes the active during takeover.

KEYEVENT=

Controls whether your IMS operator receives all XRF- related messages.

MSG indicates that noncritical-event messages and critical-event messages are sent.
NOMSG indicates that only critical-event messages are sent.

The default is NOMSG.

LNK=(interval,timeout,wtime)

Specifies the timing values for the ISC link surveillance. The default is (3,9).

interval

In the active subsystem, specifies how often (1 to 99 seconds) IMS sends signals across the ISC link.

In the alternate subsystem, specifies how often (1 to 99 seconds) IMS checks for those signals.

See Table 1 for additional information about coding the interval value.

timeout

In the alternate subsystem, specifies how long (1 to 999 seconds) IMS waits for a signal before considering a takeover.

See Table 2 for additional information about coding the timeout value.

wtime

Alternate IMS issues a warning message if the surveillance of active IMS is suspended longer then this value in seconds. Valid values are 0 - 4294967295. The default is 0. This warning message is issued repeatedly with wtime interval while long delay condition continues. A /STO SURV ALL, LNK, LOG or RDS command will disable the warning message function. If this wtime is omitted or 0 is specified, no warning message is issued in XRF alternate IMS.

LOG=(interval,timeout,wtime)

Specifies the timing values for the log surveillance. It also determines the frequency with which the alternate subsystem accesses the log, after it has caught up. The default is (1,3).

interval

In the alternate subsystem, specifies how often (1 to 99 seconds) IMS checks to see if a new log record is received from the active subsystem.

This parameter also determines the frequency with which the alternate subsystem attempts to read a new log record, after the alternate has caught up with the active. If you do not specify LOG surveillance or do not specify the interval value, the alternate subsystem waits one second between reads to the log (only if the alternate has caught up with the active).

See Table 1 for additional information about coding the interval value.

Table 1. Initializing the INTERVAL value
Subsystem	Requirement	Exception action
Alternate	Alternate interval value must be greater than or equal to active interval value.	DFS3812 issued. Alternate interval value forced to active interval value.
Alternate	Alternate interval value must be greater than or equal to alternate LOG interval value (LNK and RDS).	DFS3833 issued. Alternate interval value forced to alternate log interval value.
Alternate	Alternate interval value less than or equal to alternate RDS and LNK interval value (LOG only).	DFS3833 issued. Alternate interval value forced to alternate RDS then LNK interval value.
Alternate	Twice the interval value must be less than or equal to the alternate timeout value.	DFS3832 issued. Alternate timeout value forced to twice the interval value.
Active	Twice the interval value must be less than or equal to the active timeout value.	DFS3832 issued. Active timeout value forced to twice the interval value.

timeout

In the alternate subsystem, specifies how long (1 to 999 seconds) IMS waits for a new record, before considering a takeover.

When the alternate subsystem catches up with the active, the timeout and interval values are also used to determine a delay interval, which limits the frequency of calls to DBRC to check if an OLDS switch has occurred.

See Table 2 for additional information about coding the timeout value.

Table 2. Initializing the TIMEOUT value
Subsystem	Requirement	Exception action
Alternate	Timeout value must be greater than or equal to twice the alternate interval value.	DFS3832 issued. Alternate timeout value forced to twice the alternate interval value.
Active	Timeout value must be greater than or equal to twice the active interval value.	DFS3832 issued. Active timeout value forced to twice the active interval value.

wtime

Alternate IMS issues a warning message if the surveillance of active IMS is suspended longer then this value in seconds. Default is 0. This warning message is issued repeatedly with wtime interval while long delay condition continues. A /STO SURV ALL, LNK, LOG or RDS command will disable the warning message function. If this wtime is omitted or 0 is specified, no warning message is issued in XRF alternate IMS.

MNPS=name

Specifies the name of the MNPS ACB to use for terminal recovery. If specified, the USERVAR specification is ignored. This keyword is optional. If this specification is omitted, IMS uses the traditional XRF support and the USERVAR= specification for recovery.

MNPSPW=name

Specifies the password to use for the MNPS ACB. This password is checked by VTAM. If VTAM requires a password during VTAM system definition and no password is specified, then the MNPS ACB cannot be opened.

PSDEPAB=

Specifies whether (YES) or not (NO) prestarted BMP and IFP regions on the XRF alternate IMS are to be abnormally terminated with a U0454 abend during

/STO
BACKUP

command processing on the alternate IMS, or /CHE FREEZE processing for the active IMS.

If NO is specified, the prestarted BMP and IFP regions are terminated with return code 0. The default is YES.

RDS=(interval,timeout,wtime)

Specifies the timing values for the restart data set (RDS) surveillance. The default is (1,3).

interval

In the active subsystem, specifies how often (1 to 99 seconds) IMS writes a time stamp on the RDS.

In the alternate subsystem, specifies how often (1 to 99 seconds) IMS checks for time stamps on the RDS.

See Table 1 for additional information about coding the interval value.

timeout

In the alternate subsystem, specifies how long (1 to 999 seconds) IMS waits for a time stamp before considering a takeover.

See Table 2 for additional information about coding the timeout value.

wtime

RSENAME=xxxxxxxx

Specifies the name of the recoverable service element (RSE) containing the active and alternate IMS subsystems in an XRF complex. The RSENAME= specifications must be the same in DFSHSBxx members for the active and alternate subsystems.

The name used for the RSENAME parameter should not be the same name used for the IMSID parameter in the IMSCTRL macro for either the active or the alternate IMS subsystems in the XRF complex.

RSENAME= is required.

SURV=

Specifies the surveillance mechanisms to run in an XRF complex. The SURV= parameters in the DFSHSBxx members for the active and alternate subsystems must be the same. The default is RDS,LOG,LNK.

RDS: The alternate subsystem is to periodically check for time stamps in the RDS.
LOG: The alternate subsystem is to periodically check for new log records in the IMS log.
LNK: The alternate subsystem is to periodically check for signals coming across the ISC link.
ALL: All three surveillance mechanisms are to be used.

SWITCH=

Controls if the failure of a surveillance mechanism, VTAM, or the IRLM should cause the alternate subsystem to consider a takeover.

ABEND: Active IMS terminates with ABENDU3305 when IRLM ABEND or VTAM failure occurs. Default is no ABEND.
LNK: The absence of signals across the ISL link after a timeout period elapses causes IMS to consider a takeover.
LOG: The absence of a new log record in the IMS log after a timeout period elapses causes IMS to consider a takeover.
RDS: The absence of a new time stamp in the RDS after a timeout period elapses causes IMS to consider a takeover.
IRLM: An IRLM failure causes IMS to request a takeover.
TPEND: A VTAM failure that invokes the IMS TPEND exit routine causes IMS to request a takeover.

Specifying SWITCH=(LNK,LOG,RDS),(IRLM),(TPEND) causes IMS to request a takeover for any one of the following events:

The LNK, LOG, and RDS surveillance mechanisms all indicate a failure.
The IRLM fails.
VTAM fails and causes the IMS TPEND exit routine to be invoked.

USERVAR=xxxxxxxx

Specifies the USERVAR that VTAM uses to associate a logon message with the VTAM application name (APPLID) of the current active IMS subsystem in an XRF complex. The USERVAR= in DFSHSBxx members for the active and alternate subsystem must be the same.

USERVAR= is required if you have VTAM and are not using MNPS for XRF terminal switching.

When MNPS=name is specified, the USERVAR specification is ignored, and IMS uses MNPS for XRF terminal switching.