In the EXEC statement you need to specify the program name XUTLB or its alias DSNUTILB. For example:
//STEPEXEC DSNUTILB, ...
The PARM parameters are the same as for DSNUTILB; however, XUTLB provides the following additional parameter:
For example:
//UTILSAMP EXEC PGM=DSNUTILB,REGION=1024K, // PARM='DB5B,MFIMAG,,FBD'