The data migration batch job JCL and control cards are generated by the data migration generation utility.
If you specify the E(dit) option, you can review the generated JCL prior to submission. Here is an example of the generated JCL:
//*------------------------------------------------------------------
//* GENERATE DIM MIGRATION JOBS FOR CICS VT
//* (C) COPYRIGHT 2011
//* CIRCLE COMPUTER GROUP LIMITED
//* ALL RIGHTS RESERVED
//*------------------------------------------------------------------
//ACCTFIL EXEC PGM=VIDMIGGN,PARM='db2ssid,VIDKSDS'
//STEPLIB DD DSN=appl.driver.load,
// DISP=SHR
// DD DSN=VID.SVIDLODE,
// DISP=SHR
//REPORT DD SYSOUT=*
//MIGOUT DD DSN=appl.VIDKSDS.migrate,
// DISP=(MOD,CATLG,CATLG),
// UNIT=SYSDA,SPACE=(TRK,(1,1)),
// LRECL=80,BLKSIZE=0,DSNTYPE=LIBRARY,
// DSORG=PO
//MIGPUNCH DD DSN=appl.VIDKSDS.syspunch,
// DISP=(MOD,CATLG,CATLG),
// UNIT=SYSDA,SPACE=(TRK,(1,1)),
// LRECL=135,BLKSIZE=0
//MIGPARM DD *
J1//mig210 JOB VT,CLASS=a,MSGCLASS=a,NOTIFY=mytsoid
J2//WHERESMY JCLLIB ORDER=cvt210.SVIDCNFG.custom
VSappl.vsam.cluster
PXappl.VIDKSDS.temp
You can change the generated JCL if required but avoid changing the control cards that follow the MIGPARM DD statement.
Theoretically, you could use the ISPF option to create the generation utility the first time only. Thereafter, you could edit the JCL and change all occurrences of the initial DIM to a new DIM and submit it manually.