Need to randomize treatments

[azt5173]

My data has 3 treatments(A,B,C). I need to allocate the subject to the treatment according to a 2:1:2 randomization ratio based on a random number generated from a uniform(0,1) distribution. This is the code I have so far, I just need one random treatment for the subject, I can come up with a random number from the code but no idea how to get the treatment incorporated into it. Data set dynamic contains all of the treatments in a 2:1:2 ratio. 

Data A;
set dynamic;
do i=1 to 1;
call streaminit(123);
u=rand("Uniform");
output;
end;

Any help will be appreciated. Thank you. 
run;

[PGStats]

As @freelanceReinhard told you yesterday, use proc surveyselect with option groups=.

If that approach doesn't work for you, please tell us why.