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<h1 class="topictitle1">Share memory control</h1>
<div><p>This system value determines whether or not to allow access to
shared memory, or use mapped memory stream files.</p>
<p>This controls how users, particularly application developers, use application
programmable interfaces (APIs) that deal with sharing memory or mapped memory
stream files. Your environment may contain applications, each running different
jobs, but sharing pointers within these applications. Using these APIs provides
for better application performance and streamlines the application development
by allowing shared memory and stream files among these different applications
and jobs. However, use of these APIs could potentially pose a risk to your
system and assets. A programmer would have write access and could add, change,
and delete entries in the shared memory or stream file.</p>
<p>See <a href="#sharemem__quickref">Table 2</a> for an overview
of the shared memory control system value. </p>
<p>The following table provides a description of each of the possible settings
for this system value:</p>
<div class="tablenoborder"><table cellpadding="4" cellspacing="0" summary="" frame="border" border="1" rules="all"><caption>Table 1. Possible values for the share memory control system
value</caption><thead align="left"><tr valign="bottom"><th valign="bottom" id="d0e30">iSeries™ Navigator </th>
<th valign="bottom" id="d0e34">Character-based interface</th>
<th valign="bottom" id="d0e36">Description</th>
</tr>
</thead>
<tbody><tr><td valign="top" headers="d0e30 ">Deselected</td>
<td valign="top" headers="d0e34 ">0 (No)</td>
<td valign="top" headers="d0e36 ">Users cannot use shared memory or use mapped memory
that has write capability. Setting this value prohibits users and programmers
from using shared memory APIs, or mapped memory objects that have write capability.
Use this value in environments with higher security requirements.</td>
</tr>
<tr><td valign="top" headers="d0e30 ">Selected</td>
<td valign="top" headers="d0e34 ">1 (Yes)</td>
<td valign="top" headers="d0e36 ">Users can use shared memory, or use mapped memory that
has write capability. <span>Setting this value allows users and programmers
the ability to add, change, and delete entries in the shared memory or stream
files.</span></td>
</tr>
</tbody>
</table>
</div>
<p><span class="uicontrol">Relationship to security policy</span></p>
<p>In terms of your security policy, you need to weigh the need of application
performance with your need for security. If your company has applications
that use shared memory you should consider allowing programmers to use these
APIs. It makes application programming easier and more cost effective. However,
if your environment needs stricter security, it is recommended to limit this
capacity. </p>
<div class="p">
<div class="tablenoborder"><a name="sharemem__quickref"><!-- --></a><table cellpadding="4" cellspacing="0" summary="" id="sharemem__quickref" frame="border" border="1" rules="all"><caption>Table 2. Quick reference. Provides
overview of the shared memory control system value.</caption><thead align="left"><tr valign="bottom"><th valign="bottom" id="d0e71">iSeries Navigator name</th>
<th valign="bottom" id="d0e75">Allow use of shared or mapped memory with write capability</th>
</tr>
</thead>
<tbody><tr><td valign="top" headers="d0e71 ">Character-based interface name</td>
<td valign="top" headers="d0e75 ">QSHRMEMCTL</td>
</tr>
<tr><td valign="top" headers="d0e71 ">Authority</td>
<td valign="top" headers="d0e75 "><p>All object (*ALLOBJ)<br />
Security administrator (*SECADM)</p>
<div class="note"><span class="notetitle">Note:</span> The Security Officer (QSECOFR) user profile is shipped with
these authorities. </div>
</td>
</tr>
<tr><td valign="top" headers="d0e71 ">How to access</td>
<td valign="top" headers="d0e75 "><div class="p"><strong>iSeries Navigator</strong><ol><li>Expand <span class="menucascade"><span class="uicontrol">Security</span> &gt; <span class="uicontrol">Policies</span></span>.</li>
<li>Right click <span class="uicontrol">Security Policy</span> and select <span class="uicontrol">Properties</span>.</li>
<li>On the <span class="uicontrol">Shared Memory</span> page, you will find this option.</li>
</ol>
</div>
<div class="p"><span class="uicontrol">Character-based interface</span><ol><li>In the character-based interface, type <samp class="codeph">WRKSYSVAL QSHRMEMCTL</samp>.</li>
</ol>
</div>
</td>
</tr>
<tr><td valign="top" headers="d0e71 ">Changes take effect</td>
<td valign="top" headers="d0e75 ">Immediately</td>
</tr>
<tr><td valign="top" headers="d0e71 ">Default value</td>
<td valign="top" headers="d0e75 ">Selected (1)</td>
</tr>
<tr><td valign="top" headers="d0e71 ">Recommended values</td>
<td valign="top" headers="d0e75 ">&nbsp;</td>
</tr>
<tr><td valign="top" headers="d0e71 "><a href="rzamvlockdown.htm">Lockable</a></td>
<td valign="top" headers="d0e75 ">Yes</td>
</tr>
</tbody>
</table>
</div>
</div>
<p>For more in-depth information about this security value, see Chapter 3, <span class="q">"Security
System Values"</span> in <a href="../books/sc415302.pdf" target="_blank">Security Reference</a>. </p>
</div>
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<div class="familylinks">
<div class="parentlink"><strong>Parent topic:</strong> <a href="rzamvgensecsysval.htm" title="General security system values provide the cornerstone for your security policy.">General security system values</a></div>
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