The CICS® VR server allocates two message data sets at the server activation.
The other message data set is allocated to the DWWALT ddname as an alternate message data set. If both message data sets are full, CICS VR uses the hlq.slq.DWWMSGA.systemname data set as a current and empties it.
//*------------------------------------------------------------
//* Copy the full DWWMSG data set after switching
//*------------------------------------------------------------
//REPRO EXEC PGM=IDCAMS
//DWWMSGCP DD DSN=CICSVR.DWWMSGB.MVV1.COPY,
// DISP=(NEW,CATLG),UNIT=SYSDA,
// SPACE=(1330,200,,CONTIG),
// DCB=(RECFM=FBA,LRECL=133,BLKSIZE=1330,DSORG=PS)
//INFILE DD DSN=CICSVR.DWWMSGB.MVV1,DISP=SHR
//SYSPRINT DD SYSOUT=*
//SYSIN DD *
REPRO INFILE(INFILE) -
OUTDATASET(CICSVR.DWWMSGB.MVV1.COPY)
//*
The CICS VR server
will use the second data set until that becomes full, when it switches
back to using the first data set and starts overwriting its contents.In addition, the CICS VR server address space allocates single data sets to both the DWWDMSG and DWWDUMP ddnames. Therefore, if a problem occurs within the CICS VR server address space, various tracing and dump information can be written to the data sets allocated to the DWWDMSG and DWWDUMP ddnames that could help during problem resolution.
When the CICS VR server detects that the diagnostic message data set or the dump data set is becoming full, it rewrites it without producing any message on a console.