Flux variability of the ``10 keV feature'' of 4U 0115+63

X-ray spectra of accretion-powered X-ray pulsars can often be described using a power-law continuum with a high-energy cutoff, which might be further modified by additional spectral components. The Be X-ray binary system 4U,0115+63 is well known for having one of the highest numbers of detected harmonics of its cyclotron resonant scattering features (CRSFs), a pronounced spectral component known as the ``10,keV feature,'' and quasiperiodic oscillations (QPOs) with a period of about 500,s during outbursts. The changes in count rate by a factor of two during the ∼500,s QPOs allow us to probe the variation in the spectral components with flux. We study the ``10,keV feature'' in emission, aiming to disentangle it from the broadband continuum and CRSFs and investigate its origin. We focus on the flux-dependent behavior of the CRSF and its harmonics, and particularly the contribution of the ``10,keV feature,'' as seen in the flux-resolved analysis of two NuSTAR observations of the 2015 outburst. Comparing the flux-resolved spectra of a given observation with the respective total dataset revealed a distinct change in overall spectral shape at the position of the ``10,keV feature'' but no comparable deviation at the energies of the harmonic CRSFs. The change associated with the ``10,keV feature'' does not seem to involve its centroid energy, which remains constant within a given observation. We find indications for an anticorrelation between the continuum flux and the ratio of the ``10,keV feature'' flux to the continuum flux within each observation. The analysis strengthens previous claims that the ``10,keV feature'' shows some independence from the remaining features. This result supports the interpretation that the ``10,keV feature'' has a different formation mechanism than the continuum emission, although its origin lies within the same physical environment.