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The <var class="product">SIRENQ</var> utility is designed to be run as a started task or batch job
under all the MVS instances that can host <var class="product">Model 204</var> jobs.
<var class="product">SIRENQ</var> performs three functions that significantly enhance the
operation of <var class="product">Model 204</var> in Sysplex and multiple LPAR installations:
<ul>
<li>Verifies that <var class="product">Model 204</var> database file enqueues are automatically promoted from the
<code>SYSTEM</code> scope to the <code>SYSTEMS</code> scope on the current MVS instance.</li>

<li>Establishes an enqueue that can be "seen" by other members of a Global Resource Serialization (GRS) ring.</li>

<li>Monitors and reports to the operator the other visible instances of <var class="product">SIRENQ</var>.</li>
</ul>

For additional details about <var class="product">SIRENQ</var>, see the [[SirSafe enhanced shared DASD enqueueing#sirenq|SIRENQ]] section in the discussion of SirSafe enhancement of shared DASD enqueueing.

==Installation==
<var class="product">SIRENQ</var> is distributed as a single object deck, which may be downloaded as directed
by Technical Support or included on a product distribution tape.

<var class="product">SIRENQ</var> must be linkage edited with <code>AMODE(31)</code>. Also, <code>RMODE(ANY)</code>
is suggested.
<var class="product">SIRENQ</var> does not require APF authorization.

The following job could be used to linkage edit <var class="product">SIRENQ</var>:
<nowiki>//LINKENQ JOB CLASS=A,MSGCLASS=A
//*
//* LINK SIRENQ INTO SIRENQ.V101.LOAD, WHICH DOES
//* NOT NEED TO BE APF-AUTHORIZED
//*
//LINK EXEC PGM=HEWLKED,REGION=0M,
// PARM='LIST,LET,MAP,NCAL,SIZE=(2048K,512K),AC=0'
//SYSPRINT DD SYSOUT=*
//SYSUT1 DD UNIT=VIO,SPACE=(3200,(300,150))
//SYSLMOD DD DSN=SIRENQ.V101.LOAD,DISP=SHR
//SYSLIN DD *
<insert SIRENQ object deck>
ENTRY SIRENQ
NAME SIRENQ(R)
/*
//
</nowiki>

Before SIRENQ can be used, a <code>GRSRNLxx</code> parmlib member must be modified and
activated to override the scope specification for the enqueue requests used by <var class="product">Model 204</var>.
This is accomplished by adding the following entries in a <code>GRSRNLxx</code> member:
RNLDEF RNL(INCL) TYPE(GENERIC) QNAME(IFAMQA)
RNLDEF RNL(INCL) TYPE(GENERIC) QNAME(IFAMQB)
RNLDEF RNL(INCL) TYPE(GENERIC) QNAME(IFAMQC)


==Executing SIRENQ==
<var class="product">SIRENQ</var> can be invoked as a started task or a batch job, depending upon local preference.
If the current configuration does not correctly promote the enqueues used by
<var class="product">Model 204</var>, SIRENQ issues an error message and terminates.

<var class="product">SIRENQ</var> consumes very few system resources, although it does maintain three exclusive
enqueues that are issued with a scope of <code>SYSTEM</code> and promoted to scope of <code>SYSTEMS</code>:
IFAMQA MODEL204.SIRENQ.smfid
IFAMQB MODEL204.SIRENQ.smfid
IFAMQC MODEL204.SIRENQ.smfid

Where <var class="term">smfid</var> is the SMF system ID for the current system, or the value of
the <var>SMFID</var> parameter (described below).

The following JCL could be used to invoke SIRENQ, assuming it had previously
been linkage-edited into the data set identified by <code>STEPLIB</code>:
<nowiki>//SIRENQ JOB ,'SIRSAFE SHARED DASD',CLASS=A,MSGCLASS=A
//*
//* FIRE UP SIRENQ
//*
//TEST EXEC PGM=SIRENQ,REGION=1024K
//STEPLIB DD DSN=SIRENQ.V101.LOAD,DISP=SHR
//
</nowiki>

<var class="product">SIRENQ</var> accepts the following parameters from the <code>PARM</code> field of its <code>EXEC</code> statement:
<table>
<tr><th><var>INTERVAL=</var>nnn</th>
<td>Number of minutes to wait before re-scanning for visible systems.

The default is 5 minutes, sufficient for avoiding 522 ABENDs, while still noticing systems enteringand leaving the GRS ring.
A value of <code>0</code> eliminates the timer, and SIRENQ just waits for a <code>MODIFY</code> or <code>STOP</code> command from the operator.</td></tr>

<tr><th><var>SMFID=</var>cccc</th>
<td>If specified, this parameter provides the SMF system ID to be used by this copy of <var class="product">SIRENQ</var>. If not specified, the SMF system ID of the current system is used.
This is useful in certain hot recovery environments to avoid the need for <var>ENQCTL</var> commands to clear obsolete shared DASD enqueues.</td></tr>
</table>

==Operation==
<var class="product">SIRENQ</var> listens for operating system <code>STOP</code> or <code>MODIFY</code> commands.
If a <code>STOP</code> command is received, <var class="product">SIRENQ</var> drops its enqueues, and it exits, causing the current OS/390 instance to become invisible.

<var class="product">SIRENQ</var> processes the following <code>MODIFY</code> commands:

<table class="thJustBold">
<tr><th>REFRESH</th>
<td>Immediately rebuild the list of <var class="product">SIRENQ</var> copies seen on other systems, without waiting for the completion of the current time interval, if any.</td></tr>

<tr><th nowrap>EOD or EXIT</th>
<td>Processed as a <code>STOP</code> command: immediately drop the enqueues and exit.</td></tr>
</table>

==See also==
{{Template:SirSafe topic list}}

[[Category:SirSafe]]

SirSafe SIRENQ utility - Revision history

Admin: 1 revision: SirSafe pages

JAL: misc cleanup