  We report on the temperature dependence of the in plane magnetic penetration
depth ($\lambda_{ab}$) and first penetration field ($H_f\propto
1/\lambda_{ab}^2(T)$ for $H\|c$) in 2H-NbS$_2$ single crystals. An exponential
temperature dependence is clearly observed in $\lambda_{ab}$(T) at low
temperature, signing the presence of a fully open superconducting gap. This
compound is the only superconducting 2H-dichalcogenide which does not develop a
charge density wave (CDW). However as previously observed in 2H-NbSe$_2$, this
gap ($\Delta_{1}=1.1\, k_{B}T_{c}$) is significantly smaller than the standard
BCS weak coupling value. At higher temperature, a larger gap ($\Delta_{2}=1.8\,
k_{B}T_{c}$) has to be introduced to describe the data which are compatible
with a two gap model. The superconducting gaps are hence very similar in
NbS$_2$ and NbSe$_2$ and we show here that both of them open in the strongly
coupled Nb tubular sheets independently of the presence of a CDW or not.
