SPCORE parameter: Difference between revisions

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==Description==
==Description==
<p>
<p>
The minimum amount of storage to leave unallocated at the end of <var class="product">Model&nbsp;204</var> initialization</p>
<var>SPCORE</var> specifies the minimum amount of storage to leave unallocated at the end of <var class="product">Model&nbsp;204</var> initialization. </p>
<p>
<p>
After initialization, <var class="product">Model&nbsp;204</var> uses for this spare core include: </p>
After initialization, <var class="product">Model&nbsp;204</var> uses for this spare core include: </p>
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</ul>
</ul>
<p>
<p>
<var>SPCORE</var> sets the minimum amount of reserved virtual storage. The actual amount of reserved storage available to you during the run is <var>SPCORE</var> bytes plus the number of region size bytes that are unallocated after <var class="product">Model&nbsp;204</var> initialization. This actual amount, which you can check with the VIEW command, is often considerably greater than the CCAIN <var>SPCORE</var> value you specified. </p>
<var>SPCORE</var> sets the minimum amount of reserved virtual storage. The actual amount of reserved storage available to you during the run is <var>SPCORE</var> bytes plus the number of [[Defining the runtime environment (CCAIN)#Calculating region size|region size]] bytes that are unallocated after <var class="product">Model&nbsp;204</var> initialization. This actual amount, which you can check with the <var>[[VIEW command|VIEW]]</var> command, is often considerably greater than the CCAIN <var>SPCORE</var> value you specified. </p>
<p>
<p>
In z/OS, a number of bytes of virtual storage equal to your <var>SPCORE</var> setting is reserved above the line, and the same number is reserved below the line. </p>
In z/OS, a number of bytes of virtual storage equal to your <var>SPCORE</var> setting is reserved above the line, and the same number is reserved below the line. The BTB amount is ignored in Model 204 7.7 and higher if the <var>[[NUMBUFG parameter|NUMBUFG]]</var> parameter setting is greater than 0.</p>
<p>
<p>
You can use the <var>[[STORCUR parameter|STORCUR]]</var>, <var>[[STORINIT parameter|STORINIT]]</var>, and <var>[[STORMAX parameter|STORMAX]]</var> <var class="product">Model&nbsp;204</var> parameters to help you determine your site's storage requirements. For more information about storage allocation, see [[Performance monitoring and_tuning#Dynamic storage allocation tracking|Dynamic storage allocation tracking]].</p>
You can use the <var>[[STORCUR parameter|STORCUR]]</var>, <var>[[STORINIT parameter|STORINIT]]</var>, and <var>[[STORMAX parameter|STORMAX]]</var> <var class="product">Model&nbsp;204</var> parameters to help you determine your site's storage requirements. For more information about storage allocation, see [[Performance monitoring and tuning#Dynamic storage allocation tracking|Dynamic storage allocation tracking]].</p>
<p>
 
<b>SPCORE for Application Subsystem control blocks</b></p>
====SPCORE for Application Subsystem control blocks====
<p>
<p>
Control blocks are allocated from spare core for use by active subsystems. Use the following calculation to determine the number of bytes required for one subsystem, which can include Parallel Query Option/204 remote file subsystem members: </p>
Control blocks are allocated from spare core for use by active [[Application Subsystem development|subsystems]]. Use the following calculation to determine the number of bytes required for one subsystem, which can include [[PQO: Overview of Parallel Query Option/204|Parallel Query Option/204]] remote file subsystem members: </p>
<p class="code">228 + NRMTFILE + NFILES + (40 * <i>SCLASSes</i>) + NRMTLOCS
<p class="code">228 + NRMTFILE + NFILES + (40 * <i>SCLASSes</i>) + NRMTLOCS
     + (93 * <i>filemembers</i>)
     + (93 * <i>filemembers</i>)
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</ul>
</ul>
<p>
<p>
For information on external access to VSAM clusters, see "External file identification" in <var>[[DEFINE DATASET command|DEFINE DATASET]]</var>. </p>
For information on external access to VSAM clusters, see [[DEFINE DATASET command##External file identification|External file identification]]. </p>


====SPCORE for FLOD exits====
====SPCORE for FLOD exits====
<p>
<p>
You must allocate additional working storage space to use the FLOD exit feature. Set the <var>SPCORE</var> parameter to allow 100 bytes per FLOD exit program. </p>
You must allocate additional working storage space to use the [[FLOD exits|FLOD exit]] feature. Set the <var>SPCORE</var> parameter to allow 100 bytes per FLOD exit program. </p>


====Calculating increase to SPCORE for MQ/204 statistics====
====Calculating increase to SPCORE for MQ/204 statistics====
<p>
<p>
To calculate the additional bytes of <var>SPCORE</var> required to accommodate the MQ/204 statistics, use the following formula:</p>
To calculate the additional bytes of <var>SPCORE</var> required to accommodate the [[MQ/204 overview|MQ/204]] statistics, use the following formula:</p>
<p class="code">60 + (NUSERS * 120) = bytes of additional SPCORE required
<p class="code">60 + (NUSERS * 120) = bytes of additional SPCORE required
</p>
</p>

Revision as of 18:46, 25 August 2016

Spare core reserved

Summary

Default value
8192
Parameter type
System
Where set
On User 0's parameter line
Related products
All
Introduced
Model 204 V6.1 or earlier

Description

SPCORE specifies the minimum amount of storage to leave unallocated at the end of Model 204 initialization.

After initialization, Model 204 uses for this spare core include:

  • Small control blocks when files are opened
  • Output buffers for directed output (USE) data sets, deferred update data sets, or CCASNAP
  • Host Language Interface IFAM1 or IFAM4 application program storage
  • Application Subsystem control blocks
  • Dynamically allocated files and printer control blocks

SPCORE sets the minimum amount of reserved virtual storage. The actual amount of reserved storage available to you during the run is SPCORE bytes plus the number of region size bytes that are unallocated after Model 204 initialization. This actual amount, which you can check with the VIEW command, is often considerably greater than the CCAIN SPCORE value you specified.

In z/OS, a number of bytes of virtual storage equal to your SPCORE setting is reserved above the line, and the same number is reserved below the line. The BTB amount is ignored in Model 204 7.7 and higher if the NUMBUFG parameter setting is greater than 0.

You can use the STORCUR, STORINIT, and STORMAX Model 204 parameters to help you determine your site's storage requirements. For more information about storage allocation, see Dynamic storage allocation tracking.

SPCORE for Application Subsystem control blocks

Control blocks are allocated from spare core for use by active subsystems. Use the following calculation to determine the number of bytes required for one subsystem, which can include Parallel Query Option/204 remote file subsystem members:

228 + NRMTFILE + NFILES + (40 * SCLASSes) + NRMTLOCS + (93 * filemembers) + ((36 + (7 + SCLASSes) / 8) * (procedures + 1)) + 40 bytes for each stopped file or group

where:

  • NRMTFILE and NRMTLOCS are Model 204 parameters.
  • filemembers are the files that belong to the subsystem.
  • SCLASSes is the number of subsystem user privilege classes.
  • 40 bytes for each stopped file or group is the number of bytes returned to spare core if the subsystem is stopped or the file or group is started.

SPCORE for VSAM clusters

External access to VSAM clusters increases the requirements for dynamically allocated storage available at execution time. The amount of such storage is controlled by SPCORE in the z/OS version of Model 204. z/VSE users can refer to the discussion of the SPCORE parameter in VSAM I/O processing for further information.

SPCORE size requirements for VSAM clusters depend on the following factors:

  • Where the VSAM access method modules are to be loaded. If they are not loaded in the public system area (LPA for z/OS, SVA for z/VSE), approximately 280K bytes are required to load the VSAM modules.
  • The number of strings (STRNO) for each VSAM file and the BUFFER SPACE parameter defined in the VSAM cluster definition. The product of these parameters determines the amount of storage required for each open VSAM file.

For information on external access to VSAM clusters, see External file identification.

SPCORE for FLOD exits

You must allocate additional working storage space to use the FLOD exit feature. Set the SPCORE parameter to allow 100 bytes per FLOD exit program.

Calculating increase to SPCORE for MQ/204 statistics

To calculate the additional bytes of SPCORE required to accommodate the MQ/204 statistics, use the following formula:

60 + (NUSERS * 120) = bytes of additional SPCORE required

The initial 60 bytes are required for the system statistics block (60 bytes for MQ/204 statistics). The 120 bytes for each user includes 60 bytes for the user statistics block and 60 bytes for the since-last statistics block for MQ/204 statistics.