Ericsson 3 has got 2 different values of hysteresis i.e. HIHYST and LOHYST. If RXLEV of serving cell is greater than HYSTSEP HIHYST is used as hysteresis and if lower than HYSTSEP then LOHYST is used. Idea is to have more hysteresis when RXLEV is good and there is no chance that call will get dropped due to delay in handover and if RXLEV is low then to use lower hysteresis to avoid dragging the call.
Now if you are having ping pong handovers at a RXLEV which is lower than HYSTSEP then you may increase HYSTSEP(-ve value) to apply HIHYST to more handovers than before.
But if the cells are on different layers then you must tune LAYERTHR and LAYERHYST. The main target would be to make the IBS dominant everywhere in the building and let not be the handover to macro. If the ping pong handovers are occurring inside the building and you have enough rxlev of IBS there then you may increase LAYERTHR. But be sure that there is no spillage outside the building, in this case increasing LAYERTHR would make it serve outside the building as well.