Log and record files - syncsort_simulate_2000

You may want to use a log data set to monitor events that occur during product processing, or write records from environments that do not allow I/O. The rules language allows the products to schedule I/O requests to DD statements allocated in the DIF started task. DIF supports sequential (DSORG=PS), GDG and VSAM log files.

The LOG parameter on the DEFMSG statement can be used by the rules language to route a copy of the message to a log file allocated in the DIF started task. The DDNAME parameter on the DEFREC statement determines which DD statement in the DIF started task should receive records. For more information, examine the DEFMSG portal-2000-rules-lang-programming_defmsg.html#A7AD4C56-82246B4-7E14ADC55D10326-8565D0___bookmark431 on page 5-54 and the DEFREC portal-2000-rules-lang-programming_defrec.html#A7A52D4C-546B474-DE1487552503326-865AD0___bookmark505 on page 5-84.

Note: The size of the log records is limited by the DIF LOG parameter. By default, the records are limited to 500 bytes. For more information, examine “LOG” on page 6-10 in the Product Installation Guide.

Using Overflow Log and Record Files

When a sequential non-GDG log file has used the available space, DIF can switch to additional log files. For example, if SCC Monitor is writing records to the RTMDB file in the DIF started task and the file gets full, DIF will switch to the RTMDBA file if the DDname is available. By default, the overflow log facility will use an alphabetic sequence character added to the original file name (for example, the first overflow file concatenates an "A" to the original file name, the second uses "B", and so forth).

The DIF CLOSE command DIF CLOSE file RESET can be used to reset the log facility. When RESET is specified, the command will close an existing log file, and restart logging on the original file name. This command should be issued after dumping the original log files.

The DIF CLOSE command DIF CLOSE file SWAP can be used to force the DIF log facility to switch to the next overflow log file for non-GDG logs.

Using the Log Overflow Exit

When a log file gets full, DIF will capture the B37 condition and invoke a user exit called DIFLOGX. This exit is passed a 500 byte workarea in register 0, and a parameter list in register 1. The parameter list is a list of four-byte addresses as follows:

Parm 1—the original DDname used for the log file
Parm 2—the DDname for the current log file that has just filled
Parm 3—the data set name for the current log file that has just filled
Parm 4—the current volume name for the log file that has just filled
Parm 5—the next sequence character used to generate the overflow name
Parm 6—the address of the log file DCB that will be opened

On return, the log facility will examine the return code passed back in register 15. The return codes are handled as follows:

RC=0—the log facility will attempt to open the next overflow log file name. The name is generated using an alphabetic next sequence character concatenated with the original file name.
RC=4—returns the new DDname to use for the next log file. The name is returned in the parameter block; update Parm 2 DDname.
RC=8—disables the overflow log facility on the log file.

For more information about user exits, examine User exits on page 3-46 and the DIF EXIT command on page 7-17 in the Product Installation Guide.

GDG Log Files

DIF also supports GDG log files. If an X37 abend occurs when writing data to a GDG log file, DIF will free the current file and allocate a new data set using the +1 generation with a space value of CYL(10,10). DIF will then open and use the new dataset. Additional generations are created as needed.

The JCL below can be used to create a GDG base and the initial log file.

Note: The following JCL should be used to avoid problems on the DIF dynamic allocation request. To bypass the model DSCB requirement for non-SMS GDG data sets, the volume specified in STEP2 must be the location of the catalog (master or usercat) used by the GDG data set.

The following JCL can be found in the DIFBLDG member of the SCC sample library: DTS.R71.SLyyddd.SAMPLIB. Fields represented with bold type may need to be modified before submission.


 //DIFBLDG JOB ... (RC=0 EXPECTED)
 //STEP1   EXEC PGM=IDCAMS
 //SYSPRINT DD SYSOUT=*
 //SYSIN   DD *
 DELETE DTS.GDG.LOGFILE.*
 DELETE DTS.GDG.LOGFILE FORCE
 DEFINE GDG(NAME(DTS.GDG.LOGFILE) LIMIT(10))
 /*
 //STEP2   EXEC PGM=IEFBR14
 //DD1     DD DSN=DTS.GDG.LOGFILE,DISP=(NEW,KEEP),
 //         SPACE=(TRK,(0)),UNIT=SYSALLDA,VOL=SER=CATVOL
 //STEP3   EXEC PGM=IEFBR14
 //DD1     DD DSN=DTS.GDG.LOGFILE(+1),DISP=(NEW,CATLG),
 //         SPACE=(CYL,(10,10)),UNIT=SYSALLDA

After creating a GDG, the log file can be allocated in the DIF JCL with DISP=SHR and generation 0. If an X37 abend occurs when writing data to a GDG log file, DIF will free the current file and allocate a new data set using the +1 generation with a space value of CYL(10,10). DIF will then open and use the new dataset. Additional generations are created as needed.

A sample statement for the DIF started task:


 //SAMPLOG DD DSN=DTS.GDG.LOGFILE(0),DISP=SHR

The DIF CLOSE command DIF CLOSE file SWAP can be used to force the DIF log facility to switch to the next GDG generation. When SWAP is specified for a GDG log file, the next I/O to the log file routes records to the next generation of the GDG group. You could add F DIF,CLOSE logfile SWAP commands to your automated operations procedures to produce scheduled generations of log data (i.e., daily log files).

VSAM Log

Files

VSAM KSDS files can also be used to store log records. The rules language used by the products uses DEFREC statements to define the records being sent to the log files. The DDNAME parameter on the DEFREC determines which log file receives the record.

Note: The first character of the record sent to the VSAM log file is reserved. Typically, you should initialize the first character to a blank. If the first character is "D", an existing record using the same key will be deleted. If the first character in the record is an "R", an existing record will NOT be updated. In all other cases, the first character will be set to blank and the record written to the VSAM file. The key length and offset for the file is established by the IDCAMS define.

The following JCL can be found in the DIFVSLOG member of the SCC sample library: DTS.R71.SLyyddd.SAMPLIB. Fields represented with bold type may need to be modified before submission.


 //JOBNAME JOB ... (RC=0 EXPECTED)
 //STEP1   EXEC PGM=IDCAMS
 //SYSPRINT DD SYSOUT=*
 //SYSIN   DD *
 DEFINE CLUSTER(NAME(DTS.LOGFILE.DATABASE) + VOLUME(DTS001) SHAREOPTIONS(2) +
   RECORDSIZE(474 474) CYL(20 20) +
   INDEXED KEYS(124 4))
 LISTCAT ENTRY(DTS.LOGFILE.DATABASE) ALL
 /*

Log and record files - syncsort_simulate_2000 - Latest

Syncsort™ Storage Management Portal 2000 Rules Language Guide