/DOUBLE_SIZE[=n] D=/DOUBLE_SIZE=64

 /DOUBLE_SIZE

 The /DOUBLE_SIZE qualifier lets you specify the data size for
 floating-point DOUBLE PRECISION data declarations.  You can specify
 64 or 128 for "n".

 To request that all DOUBLE PRECISION declarations, constants,
 functions, and intrinsic procedures use the REAL(KIND=16)
 extended-precision data, specify /DOUBLE_SIZE=128.  REAL(KIND=16)
 data is stored in memory using X_floating format.

 The default is /DOUBLE_SIZE=64, which specifies that DOUBLE
 PRECISION entities use REAL(KIND=8) (64-bit) double-precision data.
 To select the floating-point format used in memory for 64-bit
 REAL(KIND=8) data, use the /FLOAT qualifier.