Changing FOCUS Limits

Determining the Number of Active FOCUS Databases

Reference:

The maximum number of FOCUS databases that can be active at one time is 256 files.

An active file is defined as a file that appears in a USE command or a file that is referenced by a FOCUS command such as MODIFY FILE fn. All files mentioned in the USE command are added to the current list of files. These files remain in the list until a subsequent USE either replaces them or clears them.

Files not previously referenced in a USE command are added to the list if they appear in the following FOCUS commands:

DEFINE	MATCH	TABLEF
FSCAN	MODIFY	? FDT
GRAPH	REBUILD	? FILE
HOLD FORMAT FOCUS	SCAN
JOIN	TABLE

Files that are referenced in FOCUS commands, but not in a USE command, successively replace each other in the file table. This allows you to execute FOCUS commands against many more files than the limit.

The following files also count as open active files: the logical file created by the COMBINE command, files referenced by LOCATION segments, cross-reference files, and files mentioned in the MODIFY FIND and LOOKUP functions.

FOCSORT is always counted toward the limit. On a FOCUS Database Server (sink machine), FOCUSSU counts as an active file.

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Reference: Active Files on the FOCUS Database Server

In SU mode, the FOCUS Database Server has its own file table that counts the active files. If the maximum number of active files allowed is exceeded, the SU session terminates. This can happen if multiple users each request different files on the server.

Files are activated on the server when a source machine issues a FOCUS command against a file on the server. A file is counted only once in the file table if more than one user requests the same file on the server.

A USE command issued by a source machine against a file on the server does not activate the file in the server's file table, but it does activate the file in the user's file table. If an individual user references more than the maximum number of files allowed, an error message appears only for that user, and SU processing is not affected.

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Reference: Error Messages for Number of Active Files

(FOC297)	THE NUMBER OF FILES EXCEEDS MAXIMUM:

The number of files provided in the FOCUS 'USE' command exceeds the current maximum allowed (usually 255). If the file has dynamically loaded sections (LOCATION or CRFILE) these must also be counted. However, files mentioned in a USE...LOCAL statement are not counted.

Occurs when a FOCUS user exceeds the limit of active files via a USE command. The user can reduce the number of active files with another USE command or a USE CLEAR command.

(FOC494)	FOCUS INSTALLATION ERROR

A FOCUS installation option was incorrectly installed, or an attempt was made to execute an unlicensed copy of FOCUS in VM/PC. Contact your FOCUS representative or your company FOCUS coordinator.

This message appears when you attempt to execute FOCUS and the option to increase the number of active files is installed incorrectly. This is most likely due to incorrect editing of the files.

(FOC683)	TOO MANY DATABASES ARE IN USE. FOCUS SESSION TERMINATED

FOCUS has a default limit of 255 databases that can be in use at one time. One database USE entry is created for each file mentioned in a USE command and one for each FOCUS or XMI file accessed. A file has been opened that exceeds the limit.

Occurs if the file table is full and the user activates a file in a way other than a USE command. This message is followed by an exit from FOCUS.

Setting the Maximum Number of Cache Pages

The maximum number of cache pages allowed per FOCUS session is 524288 pages (the hardware maximum), where each cache page is 4096 bytes in length. In CMS, cache is limited by your virtual machine size.

An individual user or batch job may specify cache pages up to one less than the maximum with the SET CACHE command:

SET CACHE = {0|n}

where:

0: Allocates no space to cache; this is the default. Cache is inactive.
n: Is the number of 4K-byte pages of contiguous storage allocated to cache memory. The minimum is two pages. The maximum value is 524287.

In normal use, the number of pages requested by users should be far less than the hardware maximum; otherwise the paging subsystem may be unfavorably affected.

Field Buffer Size

The default buffer size was increased to 32K in FOCUS 7.2 (from the 16K default in prior releases). This default is the required size for both the LINREC and DATREC buffers and may not be changed.