Yes, you can write the spline effects to a data set. It is called writing the "design matrix." I suggest you generate the design matrix by using PROC GLMSELECT, which supports an OUTDESIGN= option, like this
outdesign(addinputvars fullmodel)=DesignMatrix;
You can use the SELECTION=NONE option on the MODEL statement to force the procedure to output all the variables on the model step, in addition to the spline effects. This is shown in the section "Write the spline basis functions to a SAS data set" of the article "Regression with restricted cubic splines in SAS."
PROC GLMSELECT is one of several methods to generate a design matrix in SAS, but I like it because it also creates a macro variable that names the columns of the design matrix.
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