气量 大 = generous / forgiving spirit;
气量 小 = petty / easily offended. The metaphor is volumetric — your
气 ('spirit / breath / qi') has a
量 ('quantity / capacity'). A close cousin is
度量 (dùliàng), used the same way. The opposite character trait is captured by
小心眼 (xiǎoxīnyǎn, 'small heart-eye' = petty).
