Table of Contents

DFHMDSET

DFHMDSET (normally used in conjunction with DFHEOFMT for CICS data sets) is used to reset the last record pointer (TTR) of a disk data set so that opening the data set with DISP=MOD will allow data to be added to the end of the data set. Running DFHMDSET is only necessary if the TTR becomes invalid. This can occur if there is a system failure while the data set is open. The system keeps a TTR while the data set is open and only updates the TTR when the data set is closed or if the job abnormally ends.

DDNAME

DFHMDSET can be used with a data set whether the TTR is invalid or not. If the TTR is valid, DFHMDSET has no apparent effect.

DFHMDSET locates the end of the data by looking for an EOF (End of File) or a record that does not conform to the DCB attributes of the data set. Using DFHEOFMT to preformat the data set will ensure that DFHMDSET will be able to find the correct end of data. Thus, it is strongly recommended that DFHMDSET be used in conjunction with DFHEOFMT.

DFHMDSET can reset TTRs for up to 999 data sets in one job step. The format of the DDNAME is shown below, where xxx is a 3-digit number. This number can be no lower than 001.

DFHPSxxx

Example

Figure 8. JCL for DFHMDSET

//jobname JOB ,'your name',CLASS=class,TIME=(mm,ss),LINES=lines
/*ROUTE PRINT node.location 
// EXEC PGM=DFHMDSET 
//DFHPS001 DD DSN=data.set.name,DISP=OLD 
//DFHPS002 DD DSN=data.set.name,DISP=OLD 
//DFHPS003 DD DSN=data.set.name,DISP=OLD