HLI: Model 204 data sets in HLI jobs

Overview

This chapter describes the Model 204 data sets used in an IFAM1 or IFAM4 HLI job for application programmers who are using the Host Language Interface facility.

See HLI: Job requirements for a description of IFAM1 and IFAM4 jobs.

Model 204 data sets for IFAM1 and IFAM4 jobs

Required data sets

The following standard Model 204 data sets are required in IFAM1 and IFAM4 job runs. Model 204 requires each of these data sets for a particular function.

Model 204 data set	Function
CCAPRINT	Prints the contents of CCAIN
CCASERVR	Holds user work area for server swapping (IFAM4 only)
CCASNAP	Stores a snap dump used for error diagnostics
CCATEMP	Writes a scratch file used for temporary storage

Note: For IFAM2, these data sets are included in the Model 204 Online job.

Data sets required for a particular Model 204 facility

Except for CCAAUDIT which is optional, Model 204 requires that you specify the following data sets when using the particular facility:

Data set	Function	Required for...
CCAAUDIT	Audit log	Optional for recovery
CCAGRP	Group definitions	Permanent file groups
CCAJRN	Journal log	Recovery
CHKPOINT	Checkpoint log	Recovery
CCASTAT	Pointer to table	Security features

Specifying a Model 204 data set

To specify a particular Model 204 data set, include a job control statement that references the data set in the job setup. See HLI: Job requirements for detailed information about IFAM1 and IFAM4 jobs.

The following sections describe each of the Model 204 data sets used in HLI jobs.

CCAPRINT file

CCAPRINT defines a single sequential output data set that contains a summary of the user parameter lines and output generated by User 0 (from CCAIN in IFAM4).

The CCAPRINT file is required for IFAM1 and IFAM4 jobs.

The following guidelines apply when using CCAPRINT:

In IFAM1 and IFAM4 under z/OS, specify SYSOUT=A.
In IFAM1 under VSE, specify SYSLST.
In IFAM1 under CMS, specify PRINTER .

CCATEMP file

CCATEMP is a scratch file, either temporary or permanent, whose pages are used as work areas during a Model 204 run. The CCATEMP data set is initialized with each Model 204 run. CCATEMP must not be shared with other Model 204 jobs.

The CCATEMP file is required for IFAM1 and IFAM4 jobs.

Multiple uses for CCATEMP

Model 204 uses the scratch file for HLI jobs primarily to hold the results of IFFIND calls and record set lists.

In addition, Model 204 uses CCATEMP in the following ways:

Copies of sorted records
Copies of records sorted via IFSORT occupy pages in CCATEMP.

For a single cursor IFSTRT thread, Model 204 releases the pages in CCATEMP as the records are processed by IFGET or when IFFIND is called. For a multiple cursor IFSTRT thread, Model 204 holds the pages in CCATEMP until the sorted set is released.
File group references
File groups also use the scratch file. For IFAM1 and IFAM4 jobs that use file groups, Technical Support recommends that you allocate a scratch file of 20 pages for each thread. (Note that in IFAM1, a single thread is permitted.)

CCATEMP size requirements

When using CCATEMP, the unit type must be compatible with the installation site's page size, as summarized below.

Page size	Allowable CCATEMP units
6184	3330, 3340, 3350, 3375, 3380, 3390, or 2305-2

The size of the scratch file is related to the complexity of the retrievals executed during the run.

Note also that copies of sorted records in CCATEMP are at least as large as the original records in Table B. Coded values are expanded to character strings. You must allocate enough CCATEMP space to hold the records to be sorted.

Note: If you encounter the CCATEMP FULL error message in an IFAM1 or IFAM4 job run, increase the CCATEMP space allocation.

Using secondary CCATEMP data sets

To increase the efficiency of the scratch file for very heavy usage, you can partition CCATEMP into as many as 10 secondary data sets (CCATMP0 through CCATMP9).

You can optionally provide secondary scratch data sets for a Model 204 run using file names CCATMP0 through CCATMP9. Model 204 logically appends all the space in each available data set to CCATEMP.

Spreading the data sets over many channels and balancing the channel load improves performance. Also, partitioning makes it possible to incorporate one or more high-speed storage media for CCATEMP.

Note: If you specify CCATMP data sets in a job run, Model 204 attempts to open the secondary data sets in numerical order and stops at the first missing data set.

CCASERVR file

All runs that use server swapping (the parameter NSERVS is less than NUSERS) require one of more server data sets, which can be either temporary or permanent files.

CCASERVR is required in IFAM4 (and is not valid for use in IFAM1).

The server data sets are used for temporary storage of a user's work area when that user is swapped out of memory. See HLI: Model 204 tables for information about the user work area.

CCASNAP file

Model 204 can trap program checks and file integrity problems at appropriate times and print snap dumps of selected portions of storage to the CCASNAP data set.

These dumps are invaluable to Technical Support for locating and correcting errors.

The CCASNAP file is required for IFAM1 and IFAM4 jobs.

The following guidelines apply when using CCASNAP:

In IFAM1 and IFAM4 under z/OS, either the SYSUDUMP or SYSMDUMP data set might also be required to diagnose certain errors. Both are normally specified as SYSOUT data sets.
In IFAM1 under VM, a VMDUMP may be required in addition to CCASNAP.
In IFAM1 under VSE, CCASNAP goes to SYSLST.

CCASTAT file

CCASTAT points to a previously created password table data set.

CCASTAT is required for any IFAM1 or IFAM4 run that uses the Model 204 security features.

CCAGRP file

CCAGRP is a previously created data set that stores definitions of permanent groups.

CCAGRP is required for any IFAM1 or IFAM4 run that accesses permanent file groups.

Note: To access the definitions in the CCAGRP file, set option 2 of the SYSOPT parameter.

CCAJRNL, CCAJLOG, and CCAAUDIT files

The Model 204 journals-- CCAJRNL and the optional CCAJLOG--and audit trail (CCAAUDIT) files provide a log of information about a Model 204 run. A single execution of Model 204 can log information in a journal(s), an audit trail, or both.

The CCAJRNL, CCAJLOG, and CCAAUDIT files are optional for IFAM1 and IFAM4 jobs. However, CCAJRNL is required for the recovery facility and functions differently for recovery in IFAM1 and IFAM4.

See HLI: Model 204 recovery and checkpoints for more information about CCAJRNL, CCAJLOG, and CCAAUDIT used in HLI jobs.

CHKPOINT file

CHKPOINT is a sequential file that contains copies of Model 204 file pages before updates are applied and marker records that record the date and time when no updating activity is occurring on the system.

The CHKPOINT file is optional for IFAM1 and IFAM4 jobs. However, CHKPOINT is required for checkpointing, which is used with the recovery facility.

See HLI: Model 204 recovery and checkpoints for more information about CHKPOINT used in HLI jobs.