  Presence of closed proton and/or neutron shells causes deviation from
macroscopic properties of nuclei which are understood in terms of the liquid
drop model. It is important to investigate experimentally the stabilizing
effects of shell closure, if any, against fission. This work aims to
investigate probable effects of proton shell ($Z = 82$) closure in the compound
nucleus, in enhancing survival probability of the evaporation residues formed
in heavy ion-induced fusion-fission reactions. Evaporation residue cross
sections have been measured for the reactions $^{19}$F+$^{180}$Hf,
$^{19}$F+$^{181}$Ta and $^{19}$F+$^{182}$W from $\simeq9\%$ below to
$\simeq42\%$ above the Coulomb barrier, leading to formation of compound nuclei
with same number of neutrons ($N = 118$) but different number of protons across
$Z = 82$. Measured excitation functions have been compared with statistical
model calculation, in which reduced dissipation coefficient is the only
adjustable parameter. Evaporation residue cross section, normalized by capture
cross section, is found to decrease gradually with increasing fissility of the
compound nucleus. Measured evaporation residue cross sections require inclusion
of nuclear viscosity in the model calculations. Reduced dissipation coefficient
in the range of 1\textendash3 $\times$ $10^{21}$ s$^{-1}$ reproduces the data
quite well. No abrupt enhancement of evaporation residue cross sections has
been observed in the reaction forming compound nucleus with $Z = 82$. Thus,
this work does not find enhanced stabilizing effects of $Z = 82$ shell closure
against fission in the compound nucleus. One may attempt to measure cross
sections of individual exit channels for further confirmation of our
observation.
