I suspect that the report from FDRABR will tell you when an allocated file is 90% full - which is probably not what you want. . . This would have been handy in the "old days" when an allocation was an allocation and dynamic extension did not happen. . .
Also, as has already been mentioned, no tool will be able to predict spikes in volume. . .
If your dasd is not well managed, you may experience x37 abends due to some other processes taking the space that might have been used for your process. Indeed, even if there appears to be enough space when you "measure", something else may have taken it before your process can get to it.
On a different note, most times a sequential file is written, it is a newly created output file - not some existing file (yes MOD can be used to append, but i only use MOD intra job and not for datasets that are already "there"). If a new dataset is being written, allocating a moderate primary and overly large secondaries with RLSE should prevent the x37 and free any unneeded space when the file is closed.
Hope this helps,