You can enforce a mandatory allocation using the parameter MTLALLMGT = Yes (ADPVAL function, Chapter GPA, Group CTL).

Thanks, but we want it without allocation

If you want to prevent any WO tracking (production, material and time), then the only standard solution is the allocation. If you want to prevent a material tracking then this is standard: it's not possible to track a material if there is not enought stock (except if managed with suspended transaction / negative stock).