This JCL defines an ALIAS in the current master catalog. The alias points to the user catalog named in the RELATE clause.

Use a STEPCAT pointing to another master catalog when needed.

//DEFCAT   EXEC PGM=IDCAMS 
//* STEPCAT DD DISP=SHR etc when needed     
//SYSPRINT DD SYSOUT=*
//SYSIN    DD *        
  DEF ALIAS (NAME(PROD) RELATE(SYS1.USERCAT.PROD)) 
/*
//

//Pierre G