Customizing the Model 204 Environment

In this section:

How to:

Each Master File for a Model 204 file must have a corresponding Access File. The name of the Access File must be the same as that of the Master File. In z/OS, the Access File PDS is allocated to ddname ACCESS in the server JCL. The Access File associates a segment in the Master File with the Model 204 logical record type it describes.

The Adapter for Model 204 provides several parameters for customizing the environment and optimizing performance. These parameters control or identify Model 204 account security, the size of all adapter buffers, the size of the Model 204 FTBL buffer, null values in reports, locked records, and thread management. Information Builders strongly recommends that you set these parameters when you configure the Adapter for Model 204 (see Connection Attributes for Model 204).

However, you can also use the legacy adapter SET commands to change parameters that govern the adapter's behavior. These parameters control or identify Model 204 account security, the size of all adapter buffers, the size of the Model 204 FTBL buffer, null values in reports, locked records, and thread management. To display current adapter parameter settings, issue the adapter M204IN SET ? query command. You can issue these commands from an RPC. They remain in effect for the duration of the server client task or until you change them.

Note: If the attribute CONNECTION is provided in the Access File, then values of parameters that were placed in the appropriate SET CONNECTION_ATTRIBUTES command will be used.


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Syntax: How to Set Adapter Parameters

The syntax for adapter SET commands includes the ENGINE environment qualifier and the M204IN keyword

ENGINE M204IN SET command value

where:

command

Is an Adapter for Model 204 command.

value

Is an acceptable value for the adapter command.


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Specifying a User Account and Password

How to:

You can supply Model 204 user IDs, accounts, and passwords with the adapter M204IN SET M204ACCNT and M204PASS commands. Authorized accounts, user IDs, and passwords protect read access to Model 204 files or groups of files.

The M204IN SET M204ACCNT and M204PASS commands provide an alternative to supplying security information in encrypted Access Files. You can also use the M204IN SET M204ACCNT and M204PASS commands to override existing account and password values specified with the ACCOUNT and ACCOUNTPASS attributes in the Access File.



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Syntax: How to Specify a User Account and Password

To specify an account, issue the following from the command level

ENGINE M204IN SET M204ACCNT userid [account] 

where:

userid

Is the 1-10 character user ID by which you are known to Model 204.

account

Is a string of 1-10 characters, to be used only if an account under which the user will log in to Model 204 must be supplied.

To specify a password for an account, issue the following from the command level

ENGINE M204IN SET M204PASS password

where:

password

Is a 1- to 16-character password for the account.

Note: If you do not issue the SET commands or you leave the values blank, they default to the values of the ACCOUNT and ACCOUNTPASS attributes specified in the Access File.


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Specifying the Capacity of Adapter Buffers

How to:

You can set or change the maximum size of all adapter buffers with the M204IN SET MAXMBUFF command.

Before you issue the M204IN SET MAXMBUFF command, consider that the MAXMBUFF value:



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Syntax: How to Specify the Capacity of Adapter Buffers
ENGINE M204IN SET MAXMBUFF nnnn

where:

nnnn

Is the maximum size in bytes. For example, specify 4096 for a MAXMBUFF value of 4K. Unless you explicitly issue this command, it is not used and there is no default value.


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Controlling the Size of the FBTL Buffer

How to:

The M204IN SET FTBL command enables you to control the size of the Model 204 FTBL buffer. The LFTBL parameter, specified in the Model 204 start-up procedure, governs the size of the FTBL buffer. You can change it for the current client session only. Issue this command when a Model 204 message indicates that the LFTBL value is too small.



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Syntax: How to Control the Size of the FTBL Buffer
ENGINE M204IN SET FTBL nnnn

where:

nnnn

Is the FTBL size in bytes. For example, specify 4096 for an FTBL value of 4K.

You should set FTBL to a value larger than the previously defined Model 204 LFTBL value.

Note: The FTBL value you set applies for the current user session only; it is reset when the session is ended.


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Indicating Missing Data on Reports

How to:

With the adapter M204IN SET MISSING command, you can control the display of Model 204 null data on reports. Null data is translated into the server missing data display value. The default NODATA display value is the period (.). When the adapter MISSING attribute is set to ON, the edit specification for all IFGET calls includes an (L) format code. If Model 204 returns a zero in the first byte, the adapter considers that field to be missing.

Note: IFFIND calls contain IS PRESENT or IS NOT PRESENT criteria only when the request includes a server IF or WHERE MISSING selection test.



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Syntax: How to Indicate Missing Data on Reports
ENGINE M204IN SET MISSING {ON|OFF}

where:

ON

Uses the NODATA value to display Model 204 null data.

OFF

Null values are not represented on reports. OFF is the default value.

Note:


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Locking Records to Ensure Accurate Data Reports

When retrieving records, the Model 204 DBMS usually holds locks on the appropriate records to ensure accurate data for reports. The locks prevent other users from updating the target records while Model 204 constructs answer sets. The adapter generates standard IFFIND calls that lock the found set in SHR mode.

For certain circumstances, you can issue the adapter SET READWOL (read without locks) command to instruct the adapter to issue an IFFWOL (find without locks) HLI call. Use the following syntax to turn the setting ON:

ENGINE M204IN SET READWOL ON

For information about the design and performance considerations involved in deciding when to use the Model 204 IFFWOL command instead of the IFFIND command, consult the Model 204 Host Language Adapter Programming Guide.


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Controlling Thread Management

How to:

The adapter M204IN SET SINGLETHREAD command enables you to control Model 204 thread management during record retrieval. A thread is a communications path or link between the adapter and the Model 204 DBMS. Adapter requests (generated HLI calls) are transmitted using threads. Threads are de-allocated after each adapter request is processed.

There are two types (or modes) of thread management:



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Syntax: How to Change the Mode of Thread Management

To change the mode, issue the following from the command level

ENGINE M204IN SET SINGLETHREAD {ON|OFF}

where:

ON

Forces the adapter to use a single thread for all file access.

OFF

Allows the adapter to use multiple threads. OFF is the default value.

For example, if a request joins 10 files and the SINGLETHREAD setting is ON, only one thread is used to access all of the files. If the setting is OFF, up to 10 threads may be used. For performance reasons, the OFF setting is recommended.


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Displaying Adapter Defaults and Current Settings

The adapter M204IN SET ? query command displays adapter defaults and current settings. Issue the following:

ENGINE M204IN SET ?

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