Need the easiest way to increase the block size of a master file?

Document ID : KB000054776
Last Modified Date : 14/02/2018
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Description:

Recently getting module too large to process messages and notice that if I increase the block size of the master file these messages are eliminated.

Solution:

Using the SAMPLEJCL below the master file is backed up to a temporary master file with the new block size specified in the DCB parameter. Rename the original master file in ISPF and then rename the temporary master file to its original name.

//S1         EXEC     PGM=AFOLIBR,PARM='NRJS,NJTA'
//SYSPRINT   DD       SYSOUT=*
//OSJOB      DD       DUMMY
//LIST       DD       SYSOUT=*
//INDEX      DD       SYSOUT=*
//MASTER     DD       DSN=your.master.file,DISP=SHR
//BACKUP     DD       DSN=your.temp.master,DISP=(,CATLG),
//                    DCB=(BLKSIZE=nnnnn,DSORG=DA),
//                    SPACE=(CYL,(nnn)),VOL=SER=nnnnnn,UNIT=SYSDA
//SYSIN      DD       *
-OPT BKUPDISK,INDEX                                                
/*