Contingency and Management reserve is part of the planning process group..and I think they will vanish (used or unused) during the project closing process.

some points..

1. Contingency and Management reserves are not tied to the project work, so they don't become part of the Performance Measurement Baseline. 

2. Contingency is developed through Risk analysis.

3. Management reserve is held for unexpected growth within the currently authorized work scope, rate changes, risk handling and other program unknowns.

As per my opinion:

planning is process group

In planning determine budget is a appropriate process where these established.

and at close project or phase and close procurement they vanished.

Conengencies reserve cost  belongs to the PMB ( performance measurement baseline ) or more precisely can say belongs to cost base line.

While There is no any term like - "performance baseline" in PMBOK or elsewhere in PMI.

By mistake in short PMB sometimes may be used to say like performance baseline.

The term "work performance measurement baseline' is also the same as PMB, as per PMBOK

work performance measurements or prformance measuements are similar terms , used by PMBOK.

for reference see clause or section 7.2.2.2 and 4.2.3.1

contengiese are budget for known unknowns, included in cost baseline and considered in EV calculations.

management reserves are bugdet for unknown unknown, included in determine budget but not in cost base line nor in EV clculations.

Contengencies / management reserves are not only cost but schedule ( reserve time) also.

Original question was nicely replied by Mr. Mucool. But further discription as pointed out by Mr. deelip is correct.

Regards