code: public static synchronized int getPageSize() throws OperatingSystemException {
          if (cachedPageSize == -1) {
              switch (instance().getOperatingSystemType()) {
                  case AIX:
                  case HPUX:
                  case IBMi:
                  case Linux:
                  case Mac:
                  case Solaris:
                  case zOS:
                      cachedPageSize = getPageSizePOSIX();
                      break;
                  default:
                      throw new OperatingSystemException(Tr.formatMessage(tc, "os.pagesize.unavailable"));
              }
          }
          return cachedPageSize;
      }
docs: Get the base OS page size (this current Java process may not
  necessarily be using this page size). Not implemented on Windows.
  
  @return Page size.
  @throws OperatingSystemException Error computing page size.