The default HFS SYNC daemon interval value is 60 seconds. You may override this default by changing the SYNCDEFAULT option of the FILESYSTYPE parameter in the BPXPRMxx member of SYS1.PARMLIB. Individual HFS data sets can have an overriding SYNC value. This can be accomplished by specifying a SYNC value on the ROOT parameter, or a SYNC value on the MOUNT parameter in the BPXPRMxx member of SYS1.PARMLIB.

Refer to z/OS MVS Initialization and Tuning Reference for details on how to specify FILESYSTYPE, ROOT, and MOUNT parameters. Additionally, individual HFS data sets can be mounted by the user with the MOUNT command that specifies a SYNC value.